Tertullian

North African Christian theologian — the first major theological writer in Latin — who coined the term 'Trinity' (trinitas), wrote polemics against paganism and heresy, and is famous for 'I believe because it is absurd' (credo quia absurdum) — though the exact phrase is disputed.

Established Latin as the language of Western theology — the Trinity terminology that defines Catholic doctrine for 1,800 years was Tertullian's coinage — and developed the rigorist strand of Christian morality (what has Athens to do with Jerusalem?) that sets faith against philosophical reason.