“Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world.”
This is spoken by the figure Metonymy, and it is as if he had said, Believe not everyone that saith that he hath a gift of the holy Ghost to do the office of a Prophet. Taking occasion by the name of the Spirit, lest love and charity should be separated from the worship of God, which chiefly dependeth of his true knowledge, he returneth to that which he spake in the second Chapter touching the taking heed of Antichrists. And he will have us here to take heed of two things, the one is, that seeing there be many false prophets, we do not lightly give credit to every man: the other is, that because many men teach false things, we should not therefore believe any. We must then observe a mean, that we may be able to discern the Spirit of God, which are altogether to be followed from impure spirits which are to be eschewed.