1St. John of Damascus was one of the Early Church's most important saints, and he is considered a Doctor of the Catholic Church. He is also venerated by the Eastern Orthodox churches, who consider him one of the last of the early fathers of the church. St. John Damascene also produced An Exact Exposition of the Orthodox Faith, an invaluable source of traditional Christian theology widely accepted across the different branches and sects of Christianity. Damascene's work is in many respects a collection of accepted theology derived mostly from theologians of the 4th and 5th centuries, providing a comprehensive overview of Christian dogma. Damascene supports his writing through logic and quoting Scripture.