Heidegger's Bible Handbook: New Testament in General: The Idiom of the New Testament

11. To the external form is referred the idiom of the Books of the New Testament, that all were written in the Greek idiom. Whether the Writers conceived in the Syriac idiom, but wrote in Greek?

Idiom is also referred to the external form of the books of the New Testament. Concerning which παρέργου ὁδὸν, by-path, a few things. Now, we persist in saying that all the books of the New Testament were written in the Greek idiom, even the Gospels of Saint Matthew and Mark, and the Epistles to the Romans and to the Hebrews, which we will more fully demonstrate concerning each in its place. Neither do we think that the Sacred Writers of the New Testament conceived what they had written in another idiom, namely, Syriac, but wrote in Greek things conceived in Syriac, in such a way that there are allusions, not which are on record, but which they conceived internally, to be considered by the genuine interpreter. For, this is to be firmly held by all, that the Holy Spirit inspired his amanuenses, not only with substance, but also with individual sayings, method and expression; that they perceived the things inspired, rightly formed their conceptions, and expressed those formed conceptions in such a way that that Greek, with which they expressed themselves, is the fabric/structure, and sole canon and norm, of the faith, manners, and all our meditations, with respect to the New Testament.