"Beloved, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world." (1 John 4:1)
"Who is the liar but the one who denies that Jesus is the Christ? This is the antichrist, the one who denies the Father and the Son. (1 John 2:22)
"You will know them by their fruits. Grapes are not gathered from thorn bushes nor figs from thistles, are they? "So every good tree bears good fruit, but the bad tree bears bad fruit. "A good tree cannot produce bad fruit, nor can a bad tree produce good fruit. "Every tree that does not bear good fruit is cut down and thrown into the fire. "So then, you will know them by their fruits." ( Matt. 7:16-20)