Matthew 7:15
"Beware of the false prophets, who come to you disguised as sheep but are ravenous wolves underneath.
2 Corinthians 11:13-15
Such men are sham apostles, dishonest workmen, masquerading as apostles of Christ.
Galatians 1:8-9
But even if we or an angel from heaven preach to you good news that contradicts the good news we have preached to you, a curse upon him!
1 John 4:1
Dear friends, do not believe every inspired utterance, but test the utterances to see whether they come from God, for many false prophets have come out into the world.
Romans 1:21
for, though they knew God, they have not honored him as God or given thanks to him, but they have indulged in futile speculations, until their stupid minds have become dark.