Tertullian

Quintus Septimius Florens Tertullianus, anglicised as Tertullian (ca. 160 – ca. 220 A.D.), was a prolific early Christian author from Carthage in the Roman province of Africa. He is the first Christian author to produce an extensive corpus of Latin Christian literature. He also was a notable early Christian apologist and a polemicist against heresy. Tertullian has been called "the father of Latin Christianity".

Though conservative, he did originate and advance new theology to the early Church. He is perhaps most famous for being the oldest extant Latin writer to use the term Trinity (Latin trinitas), and giving the oldest extant formal exposition of a Trinitarian theology. Other Latin formulations that first appear in his work are "three Persons, one Substance" as the Latin "tres Personae, una Substantia" (itself from the Koine Greek "treis Hypostases, Homoousios"). Some of Tertullian's ideas were not acceptable to the orthodox Church; in later life he became a Montanist.
[Wikipedia]