2 Corinthians 11:13-15
for these are false apostles, deceitful workmen, disguised so as to pass for true apostles.
Matthew 7:15
Beware of false prophets, who to outward appearance are sheep, but inwardly they are ravenous wolves.
Philippians 3:2
be upon your guard against snarlers, against the contrivances of the crafty, against the spurious breed;
2 Peter 2:1-3
As there were false prophets among the people of Israel, there will likewise be false doctors among you, who by introducing pernicious sects, and by renouncing the Lord, who bought them, will bring 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 are gone out into the world.