Allusions to these letters go back as far as Justin Martyr, Irenaeus and Tertullian, but the first commentary derives from Clement of Alexandria. Didymus the Blind was the next significant Greek-speaking commentator, though his commentary is fully extant only in Latin translation. Many of the comments from the early centuries have been passed on to us through Latin catenae, or chain commentaries, in which a later commentator collected comments from a variety of sources and chained them together in a fashion much like that of the Ancient Christian Commentary on Scripture. Among Latin commentators on these letters, pride of place must be given to Bede the Venerable.
Because the Catholic Epistles focus on orthodox faith and morals, the Fathers drew on them as a means of defense against the rising challenge of heretics. This factor gave these letters a freshness and relevance to conditions in the fourth and fifth centuries that might otherwise seem surprising. Many of the Fathers unabashedly saw in them anticipatory attacks on Marcion and strong defenses against the Arians. They did so quite naturally because in their view truth was eternal and deviations from it had existed from the beginning. Above all, the Fathers found in the Catholic Epistles a manual for spiritual warfare, counsel for the faithful in the struggle between good and evil. In them was sound instruction in the ways of self-sacrifice, generosity and humility, through which evil could be defeated.
This is a component resource of James, 1-2 Peter, 1-3 John, Jude (Ancient Christian Commentary on Scripture, New Testament IX | ACCS).
“Augustine: Holy Scripture should be interpreted in a way which is in complete agreement with those who understood it and not in a way which seems to be inconsistent to those who are least familiar with it. Paul said that a man is justified through faith without the works of the law, but not without those works of which James speaks.” (Pages 30–31)
“Peter means that God has acted to redeem us without any help from us. His mercy is great enough to be able to forgive every sin which has been committed in thought, word and deed, from the beginning to the end of the world.” (Page 68)
“If you want to exercise the priesthood of your soul, do not let the fire depart from your altar.” (Page 87)
“To summarize all this, we may say that defenders of the authenticity of the Catholic Epistles relied mainly on historical considerations, whereas those who rejected them preferred literary (stylistic) arguments.” (Page xx)
“For when he says ‘which was from the beginning’ he is referring to the generation of the Son which has no beginning, because he exists coeternally with the Father.” (Page 166)