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Theology: The Definitive Guide to Getting Started

Theology: the world’s most important topic

The word “theology” may have only four syllables, but it’s a big word—a very big word. Theology is the study of God. But anytime you set out to study someone as large as the creator of the universe, it’s bound to be overwhelming.

Some of the most significant thinkers in human history—from St. Augustine to Martin Luther to Dietrich Bonhoeffer—gave their lives to thinking, writing, and teaching about theology. Their theological expositions impacted the direction of the church for 2,000-plus years and transformed Western civilization.

Yet as big as theology is, it’s the impact it has on the believer’s decisions every day that makes it so consequential. What we believe about God, Jesus, the Bible, the church, and several other issues has a profound impact on how we live. Our theological convictions shape our feelings. And our feelings help to form our actions.

Theology literally touches every part of our lives.

What is theology?

At its core, theology (as mentioned above) is “the study of God.” But for the Christian, theology means something more specific: theology is the study of how God reveals himself in canonical Scripture—and of how Christian people might use that revelation to answer the questions of life.

In his Systematic Theology: An Introduction to Christian Belief, evangelical theologian John Frame suggests a definition of theology along these lines: “Theology is the application of Scripture, by persons, to every area of life.”

Theology must be biblical, and its purpose is deeply tied to the church, to the actual lives of real Christians. We shouldn’t involve ourselves in theology simply to understand biblical principles and debate doctrines. Theology changes how we see the world and how we live. James tells us to be doers of the word, not just hearers (1:22). When we keep the local church and its needs in mind as we study and communicate theology, we help the Christian body to develop in Christlikeness and fulfill its Great Commission responsibilities.

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Types of theology

Natural theology

In Dictionary of Theological Terms, Alan Cairns defines natural theology as, “The science which on the principles of human reason and conscience, considering the evidences of God’s works in creation and providence, seeks to construct a scientific knowledge of God—i.e., it seeks to ascertain (1) Is there a God? (2) What is his nature? (3) In what relation does he stand to man?” Natural theology includes all the ways we can know about God outside his specific revelation through the Bible.

Paul describes this in Romans 1:20: “For his invisible attributes, that is, his eternal power and divine nature, have been clearly seen since the creation of the world, being understood through what he has made. As a result, people are without excuse” (CSB).

While most theologians have accepted that certain truths about God’s existence, power, and character can be obtained through natural theology (as the psalmist tells us in 19:1: “The heavens declare the glory of God, and the expanse proclaims the work of his hands”), most theologians have also understood that the limits of human intellect mean that the information we can learn on our own about God is hazy at best.

For example, according to the Pocket Dictionary of the Reformed Tradition, John Calvin believed that “humans have an awareness of God (sensus divinitatis) and encounter some of his attributes in nature, but sinful minds inevitably distort this awareness and prevent saving knowledge.”

Historical theology

Historical theology represents the marriage of theology and Church history. The discipline focuses on the development of theological doctrines throughout more than 2,000 years of Church history.

A. C. Thiselton writes in the Thiselton Companion to Christian Theology: “Theology is never purely abstract. It answers questions that arise from a series of specific contexts and events.” Historical theology doesn’t focus on the people or the events of Church history but the ideas that sprung from these events and how they developed over time.

While the development of these historical doctrines of the Christian church never trumps biblical revelation, they do ensure we’re interpreting Scripture within the bounds of orthodoxy. We recognize that we study the Bible and live out its principles surrounded by a “great cloud of witnesses” (Heb 12:1) and that we aren’t the only ones whom Christ’s Spirit guides “into all truth” (John 16:13).

Historical theology is often divided into subsets depending upon the era. Anglican theologian Alister McGrath describes four such eras in his book Historical Theology: the Patristic, Medieval, Reformation, and Modern. All major doctrines of the Christian faith show development and refinement throughout these four eras.

Systematic theology

The systematic approach studies the entire scope of the Bible by looking at everything Scripture teaches about a particular topic or issue and describes the biblical and historical development of the theological doctrines. According to the Lexham Bible Dictionary, it’s “an approach to the Bible that seeks to draw biblical teachings and themes into a self-consistent, coherent whole, in conversation with the history of Christian theological reflection and contemporary issues confronting the church.”

Because of the frequent dependence upon systematic theology to develop Christian creeds and doctrinal statements, it’s a popular approach to theology that has led to some of the most significant theological works in Church history, including Thomas Aquinas’ Summa Theologica, Herman Bavinck’s Reformed Dogmatics, John Calvin’s Institutes of Christian Religion, and Karl Barth’s Church Dogmatics.

At times, systematic theologians have needed to defend their discipline from other theologians who accuse them of bending Scripture to squeeze doctrine into artificial theological systems. At its best, though, systematic theologians help the church to speak authoritatively and biblically on specific topics of consequence.

Biblical theology

As described in the Holman Illustrated Bible Dictionary, biblical theology is the “discussion of what the Bible itself teaches about God and his dealings with human beings and the rest of creation.” Biblical theology provides the foundation for natural, systematic, and historical theology because it represents the exegetical work required for all theological study.

Although believers have developed biblical theology for as long as the Bible has existed, it became a separate field of study in the eighteenth century in reaction against dogmatic (or systematic) theology. The Oxford Dictionary of the Christian Church defines five typical characteristics of biblical theology:

  1. Biblical concepts take preference over all others.
  2. Biblical concepts are sufficient for all “essential purposes.”
  3. God’s work in history is the primary medium of revelation.
  4. It emphasizes the “inner coherence of the biblical material.”
  5. It tends toward a conservative attitude about the historical integrity of Scripture.

In the church of Jesus Christ, there can and should be no non-theologians.
—Karl Barth
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Key theologians

While many theologians through the ages have impacted the development of the church’s doctrinal teachings, certain figures have played an outsized role. It’s hard to narrow the most influential theologians to a list of three. Most theologians exert influence over a single theological tradition or denomination. Yet three theologians—Paul, Augustine, and Martin Luther—impacted all or most of the church. They share several common characteristics, including dramatic, iconic conversion experiences and theologies formed in the fires of pastoral and/or missional ministry.


It’s impossible to overstate the impact of the apostle Paul on the theological development of the church. Not only did he write most of the New Testament, but his letters have been the doctrinal center of the major theological works of the past 2,000 years. 

Born Saul of Tarsus (on the southern coast of modern-day Turkey), Paul learned Judaism under the teaching of the influential Jewish leader Gamaliel. The passionate persecutor of the early Church converted to Christianity after encountering a risen Jesus on the road to Damascus as described in Acts 9. He became the most proficient missionary in Church history, traveling throughout the known world to share the gospel. His letters to the churches he started became the basis for much of the New Testament. Although the letters were written to address specific issues within the churches, the principles he taught have shaped the church’s teachings on numerous topics. 

The Lexham Bible Dictionary describes the book of Romans as the “text that best resembles a fully voiced theological manifesto.” It’s also likely his most controversial letter. In it, Paul addresses his theological views on salvation, faith, sin and judgment, the law, and more. 

Paul’s letter to the Romans played a pivotal role in Augustine’s and Martin Luther’s conversions.


The famed bishop of Hippo was likely the most influential patristic theologian. Born in North Africa to a pagan father and a devout Christian mother, Augustine’s early study was in rhetoric, a key way to advance in public administration, according to The Westminster Dictionary of Theologians. His early study led him to embrace Manichaeism—a dualistic religious system with elements of Gnosticism, Christianity, and paganism—but after a dramatic experience in the Garden of Milan in AD 386, he converted to Christianity.

Among the most prolific theological writers in Church history, Augustine leaned on his intellectual and rhetorical skills to deal with the Donatist and Pelagian controversies. His major theological works include The City of God, On the Trinity, and On Christian Doctrine.

Augustine is the father of Augustinianism, which The Pocket Dictionary of Theological Terms defines as:A system of thought [that] essentially starts with the complete sinfulness of humankind (depravity), which leaves humans unable to respond in faith toward God.” While Augustinianism significantly impacted the development of medieval theology, it also influenced many of the reformers of fifteenth- and sixteenth-century Europe (particularly Martin Luther and John Calvin).
Augustinian theology is often set against Pelagianism, the teachings of Augustine’s contemporaneous rival who believed people were “capable of avoiding sin and choosing to live righteous lives even apart from God’s grace,” according to The Lexham Bible Dictionary. It’s a battle Augustine clearly won. Most of the Christian church considers Pelagianism heretical today.

Martin Luther

Martin Luther may be the West’s most influential single person since New Testament times. Originally an Augustinian monk, Luther first adopted the theological belief of nominalism, which gives man a specific but limited role in his own justification. The Oxford Dictionary of the Christian Church says of Luther, “He came to believe that man is unable to respond to God without divine grace, and that man can be justified only through faith (per solam fidem), by the merits of Christ imputed to him: works or religious observance are irrelevant.” A life-altering encounter with the truth of Romans 1:17 and Paul’s treatise on the righteousness of God set Luther’s theology on a new track that would have monumental consequences for Christendom. In October 1517 Luther famously nailed 95 theses on indulgences on the door of the Wittenberg Church, which set him on a collision course against Pope Leo X and the sixteenth-century Roman Catholic Church. 

Over the next three decades, Luther’s doctrinal exposition (along with his collaborator Philip Melanchthon) not only rocked the Christian church but the entirety of the Western world. He is widely credited as the founder of what became the Protestant Reformation, forming the third major branch of Christianity (along with Roman Catholicism and Eastern Orthodoxy). Among Luther’s most important books (by Luther’s own appraisal) are The Bondage of the Will, his Catechism, and his commentaries on Galatians and John 14–16.

Luther’s theological legacy is often called Lutheranism. According to The Pocket Dictionary of the Reformed Tradition, “While Lutheranism holds to the solas of the Reformation (sola fide, sola gratia, sola scriptura, soli deo gloria, solus Christus), it historically differs from Calvinism in such areas as its view of the consubstantiation of Christ’s body and blood in the Lord’s Supper, the ubiquity of Christ’s humanity in opposition to extra calvinisticum, and the distinctive separation of law and gospel.” 
The New Dictionary of Theology describes soteriology (the theology of human salvation) and the authority of God’s Word as the most influential doctrines of Lutheran theology.

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Key theological questions for each doctrinal topic

Although various theological streams within the church define their beliefs differently, most will agree on the boundaries of the eight to ten major doctrines of the Christian faith. Many of these topics are outlined in the great creeds of early Christianity. While there is significant agreement around these topics, orthodox Christians also have diverse responses to many of the questions below.


All significant theological reflection begins with a clarity around how we come to know truth. Many of the great questions we have around God center around our view of revelation. Under this broad theological topic are questions that relate to how God communicates with humanity, including:

  • How do we gain knowledge about God?
  • What is truth and how can we know it?
  • How does God reveal himself to humanity?
  • What is the mode of biblical inspiration?
  • How did God use humans in the process of creating biblical texts?
  • How does God intend us to understand the Bible?
  • How should we understand the scientific, historical, and theological truthfulness of Scripture?
  • What is the place of the Bible within Christian discipleship?


Just as the biblical story begins with the creative acts of God in Genesis 1 and 2, the theological story the Bible centers on who God is and how he relates with humanity. Questions about who God is have remained some of the most important in all of Christian theology.

  • Who is God?
  • What are the character traits that best describe him?
  • In what ways is God like us?
  • In what ways is he not?
  • What is the Trinity and how does it describe the nature of God?
  • How did God create the universe?
  • How does God exert control over history?
  • How can we communicate with God?


The central figure of Christian history is the second person of the Trinity—Jesus. For 2,000 years, theologians have debated who Jesus is, why he mattered, and why he continues to matter today. The most important theological questions surrounding Jesus are:

  • How should we understand the divinity and humanity of Jesus?
  • In what way did Jesus exist before coming to Earth?
  • How should we understand the incarnation of Jesus?
  • What was the meaning of Jesus’ life, death, and resurrection?
  • What did the death of Jesus mean for the original readers of the New Testament, and what does it mean for us today?
  • In what ways did his death atone for human sin?
  • What was the nature of Jesus’ resurrection, and what does it mean for us today?

The Holy Spirit

Of the three persons of the Trinity, the Holy Spirit has likely been the most neglected in theological study throughout Church history. Today, with more attention on the doctrine of the Holy Spirit, it’s one of the most hotly debated and divisive in the church. You’ll find broad agreement on some of these questions but also significant differences:

  • In what ways did the Holy Spirit act prior to the day of Pentecost as described in Acts 2?
  • What does the Bible mean when it describes the filling of the Holy Spirit?
  • What are the gifts of the Holy Spirit, how are they distributed, and what are they used for?
  • How do we understand the charismatic gifts of the Spirit, and what is their place in the church today?
  • What is the unique role of the Holy Spirit in spiritual growth and the ongoing life of the Christian?


Humans have long questioned how they came to exist, why they exist, their purpose, and the nature of the obstacles that prevent them from achieving their purpose. While those issues were debated long before Christian history began, they’ve been among the most hotly discussed in Church history as well. These questions include:

  • What is the purpose of humanity?
  • What is sin and how does it impact humans?
  • Why did God create humans both male and female, and are their roles intended to be the same or complementary?


Because of the eternal consequences of theological discussion around salvation, the doctrine of salvation is particularly disputed in the contemporary church. The doctrine of salvation contains some of the widest areas of disagreement among orthodox Christians. Some of the most important questions in this doctrine are:

  • Why do humans need salvation?
  • How did Jesus’ work on the cross provide for human salvation?
  • What is the gospel?
  • What is election, and when does it happen?
  • What are the past (justification), present (sanctification), and future (glorification) aspects of salvation?
  • What is the nature of the afterlife, and what determines the experience of the afterlife for humanity?
  • What, if any, is the human role in salvation?


Most divisions within Church history have resulted from disagreements on ecclesiology (the theological study of the church). Therefore, the doctrine of the church has historically been one of the most important theological topics. With the coming of the digital age and the church’s response to Western cultural changes of the past half century, new issues in ecclesiology have emerged. Some of the most important questions for the church throughout the years have been:

  • What is a local church?
  • What is the nature of the universal Church?
  • What are the ordinances and/or sacraments of the church, and what is their significance for the church and for individual Christians?
  • What are the offices of the local and universal Church, and what are the qualifications for those offices?
  • What are the roles of different officers of the local church?
  • What is the purpose (or purposes) of the church?
  • Which, if any, are preeminent in the life of the church?
  • What is the role of the church and the nature of its mission in the world?

Last things

Historically, the doctrine of last things (or as others call it, the doctrine of Christian hope or eschatology) has had increased interest in periods of persecution and/or cultural estrangement. In recent years, particularly among evangelical Christians, popular-level books and films have helped to spur on discussions about these topics. Significant questions around this doctrine include:

  • What is the Christian theology of time (linear vs. cyclical)?
  • How should Christians understand the literalness of the biblical description of end-time events?
  • When and how will Christ return?
  • What is the millennial reign of Christ, and how will/does the church relate to it?

Resources referenced + others to help you study theology

Dig into theological resources to help you understand and communicate doctrine effectively.

Lexham Bible Dictionary

Lexham Bible Dictionary

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Summa Theologica (22 vols.)

Summa Theologica (22 vols.)

Regular price: $49.99

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Institutes of the Christian Religion

Institutes of the Christian Religion

Regular price: $29.99

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Barth’s Church Dogmatics (31 vols.)

Barth’s Church Dogmatics (31 vols.)

Regular price: $299.99

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Holman Illustrated Bible Dictionary

Holman Illustrated Bible Dictionary

Regular price: $20.99

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The Oxford Dictionary of the Christian Church, rev. ed.

The Oxford Dictionary of the Christian Church, rev. ed.

Regular price: $109.99

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The Westminster Dictionary of Theologians

The Westminster Dictionary of Theologians

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The Bondage of the Will

The Bondage of the Will

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New Dictionary of Theology: Historical and Systematic, 2nd ed.

New Dictionary of Theology: Historical and Systematic, 2nd ed.

Regular price: $37.99

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Systematic Theology: An Introduction to Biblical Doctrine, 2nd ed.

Systematic Theology: An Introduction to Biblical Doctrine, 2nd ed.

Regular price: $47.99

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Theology: Foundational Certificate Program

Theology: Foundational Certificate Program

Regular price: $999.99

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Bonhoeffer for Armchair Theologians

Bonhoeffer for Armchair Theologians

Regular price: $10.99

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Systematic Theology: An Introduction to Christian Belief

Systematic Theology: An Introduction to Christian Belief

Regular price: $39.99

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Dictionary of Theological Terms

Dictionary of Theological Terms

Regular price: $35.99

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Pocket Dictionary of the Reformed Tradition

Pocket Dictionary of the Reformed Tradition

Regular price: $7.99

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The Thiselton Companion to Christian Theology

The Thiselton Companion to Christian Theology

Regular price: $59.99

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4 Steps to developing theological convictions


Search Scripture

Look at history

Write it down


The practice of developing theological convictions isn’t primarily an academic exercise—it’s a spiritual one. Truth—the kind of truth that changes lives—comes from God and him alone. John the Baptist understood this when he said: “No one can receive anything unless it has been given to him from heaven” (John 3:27 CSB).

Invite God into your theological reflection from the start. Let him know you want to know him. That’s why you’re studying theology. Ask him to open your mind and your heart to truth from his Word.

Search Scripture

After talking to God about your theological study, search the Bible. God’s Word doesn’t just inform our theological convictions. It’s the basis for them. All we know about the doctrines of Christianity flow from Scripture.

As you try to understand what the Bible says about a specific topic, you’ll want to take a “verse-with-verse” approach that looks throughout Scripture to see what it says about the topic. At a basic level, a concordance can be a great way to start. A typical concordance will organize biblical verses by subject. Take the topic you’re going to study and look up a variety of verses on it and other related subjects. For example, if you’re going to study the topic of election, you might study what the Bible says about election, salvation, predestination, etc. Usually you’ll want to look at instances where the terms are used in various parts of speech (verbs, nouns, etc.).

But one of the advantages of studying theology in the twenty-first century is the ability to use digital tools to amplify your biblical research. Software like Logos gives you an opportunity to not only search the full swath of Scripture in a few taps but to add several digital tools to your Bible study. With Logos, you can study a passage in its original language (even with a limited language background), find related verses, and even see how others interpret the passage in just a couple of clicks.

Look at history

While biblical research is always your starting point, involving the reflection of theologians from the past helps to ensure you’re staying within theological orthodoxy. For 2,000 years Christian theologians have studied and debated what Scripture teaches on important doctrines. You will not discover anything that is biblical and new to the church. You may apply Scripture to new problems, but you’ll never discover new theology.

That’s why it’s critical to see what Church leaders have said in the past about topics you’re studying. Don’t just look at one era of Church history either. It’s important to look at theologians from the PatristicMedievalReformational, and the Modern eras of Church history.

This is another area where digital tools come in handy. With Logos software, you can search theological resources for topics in a few simple clicks. You can also lean on the Logos Theology Guide to research theological topics in all of your resources. With the Theology Guide, you can easily move between various theological texts and compare views of theologians across different eras.

Write it down

Writing down your theological convictions has multiple advantages. First, it allows you to clearly synthesize your thoughts. Documenting your doctrinal convictions forces you to keep a consistent and reliable argument as you describe your beliefs.

Writing your theology also helps you share it. While it’s important to study theology for your own spiritual growth, ultimately you want to help others to learn more about God through your reflection. Even if your plan is to share it orally (through a sermon, lecture, or speech), a well-written doctrinal description will help you as you do so. You may even want to distribute your theological reflection through a book, blog series, article, or some other public manner.

We’re all theologians

Every believer throughout the ages who has ever cracked open a Bible is a theologian. As we read the Word to discover more about God and how he is at work in the world, we’re most assuredly “doing theology.”

But diving into the Bible is just the beginning of doing theology. When Paul described to young Timothy the goal of the Bible in 2 Timothy 3:16–17, he said: “All Scripture is inspired by God, and is profitable for teaching, for rebuking, for correcting, for training in righteousness, so that the man of God may be complete, equipped for every good work” (CSB). We study what the Scriptures say about God so that we might know God and do his work in the world.

As theologian Sam Storms once said: “The goal of theology isn’t knowledge but worship.”

More resources about theology

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Written by
Tobin Perry

Tobin Perry has spent over 20 years as a writer and editor for faith-based audiences. He has written for Christianity Today, Baptist Press, Saddleback Church, the North American Mission Board, and more. He has also served as a lead pastor of a small church in Southern Indiana and a church planting intern in Seattle, Washington. Tobin has a Bachelor of Journalism degree from the University of Missouri and a Master of Divinity degree from Golden Gate Baptist Theological Seminary (now Gateway Seminary). He lives in Evansville, Indiana with his wife and three children.

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Written by Tobin Perry