Theophilus of Antioch was a Christian theologian and bishop of Antioch in the late 2nd century. He is best known for his work "Ad Autolycum," a defense of Christianity against pagan beliefs. Theophilus aimed to demonstrate the rationality of the Christian faith and its compatibility with philosophy. In his writings, Theophilus emphasized the importance of the Old Testament and the role of Jesus Christ as the fulfillment of biblical prophecy. He is considered one of the early apologists, contributing to the development of Christian thought and the defense of the faith during a time of persecution.