Didymus the Blind, on 1John 4:1

“Dearly beloved, believe not every spirit, but try the spirits if they be of God: because many false prophets are gone out into the world.”

“Just as in ancient Israel there were some prophets who spoke the word of God and others who did not, so also, as soon as the apostles appeared, speaking in Christ and having the Holy Spirit whom the Lord had given to them, many false apostles were sent by the devil to counterfeit the teaching of the gospel. It is essential to have that gift of the Holy Spirit which is called the discernment of spirits in order to have the ability to test the spirits, to see which ones are to be believed and which ones are to be rejected.”

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