Augustine of Hippo, on 1John 4:2

“By this is the spirit of God known. Every spirit which confesseth that Jesus Christ is come in the flesh, is of God:”

“There remains then the test by which it is to be proved to be the Spirit of God. He has indeed set down a sign, and this, be-like, difficult: let us see, however. We are to recur to that charity; it is that which teacheth us, because it is the unction. However, what saith he here? "Prove the spirits, whether they be from God: because many false prophets have gone out into this world." Now there are all heretics and all schismatics. How then am I to prove the spirit? He goes on: "In this is known the Spirit of God." Wake up the ears of your heart. We were at a loss; we were saying, Who knows? who discerns? Behold, he is about to tell the sign.”

Imported from an open dataset — not yet checked against the printed edition.