c. 180 · Irenaeus of Lyons, Against Heresies 5.6.1
Neither is the spirit a man, for it is called the spirit, and not a man; but the commingling and union of all these constitutes the perfect man. And for this cause does the apostle, explaining himself, make it clear that the saved man is a complete man as well as a spiritual man; saying thus in the first Epistle to the Thessalonians, “Now the God of peace sanctify you perfect (perfectos); and may your spirit, and soul, and body be preserved whole without complaint to the coming of the Lord Jesus Christ.” Now what was his object in praying that these three—that is, soul, body, and spirit—might be preserved to the coming of the Lord, unless he was aware of the [future] reintegration and union of the three, and [that they should be heirs of] one and the same salvation? For this cause also he declares that those are “the perfect” who present unto the Lord the three [component parts] without offence. Those, then, are the perfect who have had the Spirit of God remaining in them, and have preserved their souls and bodies blameless, holding fast the faith of God, that is, that faith which is [directed] towards God, and maintaining righteous dealings with respect to their neighbours.