Tertullian

Tertullian was a North African Christian writer and the first major theologian to write extensively in Latin. His apologetic, doctrinal, moral, and polemical works helped establish Latin Christian vocabulary, including influential formulations concerning the Trinity. He defended Christian belief against pagan criticism and heresy with sharp legal and rhetorical skill. Later in life he aligned himself with the rigorist New Prophecy, or Montanist, movement, and he is therefore not ordinarily honored as a saint despite his immense historical importance.