The Vital Forces of Christianity and Islam contains six studies by missionaries to Muslims, a concluding essay by Duncan Macdonald, as well as an introduction by Samuel M. Zwemer. These missionaries worked in Cairo, Urumia, Sumatra, Beirut, Lahore, and Zanzibar. Topics include specific points in Islam with which Muslims are dissatisfied, elements in the Christian gospel and Christian life which appeal to Muslims, as well as the major points that awaken opposition and contention, and much more.