2 Corinthians 11:13-15
For such men are false apostles, deceitful workers, transforming themselves into apostles of Christ;
Matthew 7:15
"Beware of false prophets, who, indeed, come to you in sheep's clothing, but within are ravening wolves.
Philippians 3:2
Beware of the dogs, beware of the evil-workers, beware of the mutilation.
2 Peter 2:1-3
But there arose false prophets also among the people, as among you also there will be false teachers, who, indeed, will stealthily bring in destructive heresies, denying even the Master Who bought them, bringing upon themselves swift destruction:
1 John 4:1
Beloved, believe not every spirit, but try the spirits, whether they are of God; because many false prophets have gone forth into the world.