The writings of the Church Fathers comprise by far the bulkiest corpus in extant Latin and Greek literature. A great deal of what the Fathers wrote has to do with exegesis of the Bible, a text long seen as written in a language very distant from the formal high style of Greek and Latin literary texts. Patristic exegesis is of course mainly theologic, doctrinal, pastoral, but even so it often discusses matters of language in fashion interesting to the modern linguist. Of course some scholarship on these issues has been produced, some excellent, mostly concentrating on the sparse evidence writers such as Jerome or Augustine, in Latin, have brought to bear on ‘vulgar’ and spoken latin, especially quoting lexical items not used by Classical authors or not found in written Latin before. In this paper, however, I attempt to dwell mostly on some of this evidence as bearing on variation and register, the value of these exegetical writings and the pitfalls lurching scholars attempting to use them.