Matthew 7:15
"Beware of false prophets, who come to you in sheep's clothing, but inwardly they are ravenous wolves.
2 Corinthians 11:13-15
For such men are false apostles, deceitful workmen, disguising themselves as apostles of Christ.
Galatians 1:8-9
But even if we, or an angel from heaven, should preach to you a gospel contrary to what we preached to you, let him be accursed!
1 John 4:1
Beloved, do not believe every spirit, but test the spirits to see whether they are of God; because many false prophets have gone out into the world.
Romans 1:21
for although they knew God they did not honor him as God or give thanks to him, but they became futile in their thinking, and their foolish hearts were darkened.