The competition with Gnosticism compelled the early Christians to define and defend their faith, and supplied certain of the technical terms of later theology. With the aid of apologists and teachers, the Church worked itself free from Gnosticism.
Quintus Septimius Florens Tertullian (c. 160- c. 220) was born in Carthage, North Africa. He studied law as a young man. In about 195 he converted to Christianity and spent the rest of his life utilizing his skills as a rhetorician to defend the faith against pagan philosophies and heresies.
Irenaeus (c. 2nd century) was born somewhere in western Asia Minor, probably Smyrna. He studied religion and philosophy under Polycarp, the bishop of Smyrna.