Matthew 7:15
But beware of false prophets, who come to you in sheep's clothing, but inwardly they are rapacious wolves.
2 Corinthians 11:13-15
For such are false apostles, deceitful workers, transforming themselves into the apostles of Christ.
Galatians 1:8-9
But indeed if we, or an angel from heaven, may preach unto you any other gospel except that which we have preached unto you, let him be accursed.
1 John 4:1
Beloved, believe not every spirit, but prove the spirits if they are of God: because many false prophets have gone out into the world.
Romans 1:21
because, knowing God, they did not glorify Him as God, neither were they thankful; but they became vain in their reasonings, and their foolish heart was darkened.