2 Corinthians 11:13-15
For men of this stamp are sham apostles, dishonest workmen, assuming the garb of Apostles of Christ.
Matthew 7:15
"Beware of the false teachers--men who come to you in sheep's fleeces, but beneath that disguise they are ravenous wolves.
Philippians 3:2
Beware of 'the dogs,' the bad workmen, the self-mutilators.
2 Peter 2:1-3
But there were also false prophets among the people, as there will be teachers of falsehood among you also, who will cunningly introduce fatal divisions, disowning even the Sovereign Lord who has redeemed them, and bringing on themselves swift destruction.
1 John 4:1
Dear friends, do not believe every spirit, but put the spirits to the test to see whether they are from God; for many false teachers have gone out into the world.