Acts 13:10
and said, "O child of the devil and enemy of all righteousness! You are full of all kinds of deceit and trickery. Will you never stop perverting the straight ways of the Lord?
The Lord is the straight way and other ways are perverted.
"Woe to you, teachers of the law and Pharisees, you hypocrites! You travel over land and sea to win a single convert, and when you have succeeded, you make them twice as much a child of hell as you are."
How does that happen? Think about it.
Galatians 2:11 When Cephas came to Antioch, I opposed him to his face, because he stood condemned. 12 For before certain men came from James, he used to eat with the Gentiles. But when they arrived, he began to draw back and separate himself from the Gentiles because he was afraid of those who belonged to the circumcision group. 13 The other Jews joined him in his hypocrisy, so that by their hypocrisy even Barnabas was led astray.
Philipians 1:17 The former preach Christ out of selfish ambition, not sincerely, supposing that they can stir up trouble for me while I am in chains.
2 Thessalonians 1:6 God is just: He will pay back trouble to those who trouble you
1 Timothy 1:3 As I urged you when I went into Macedonia, stay there in Ephesus so that you may command certain men not to teach false doctrines any longer
2 Timothy 2:17 Their teaching will spread like gangrene. Among them are Hymenaeus and Philetus,
1 John 4:1 Dear friends, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world.
Galatians 1:8-9 But even if we or an angel from heaven should preach a gospel other than the one we preached to you, let them be under God’s curse! 9 As we have already said, so now I say again: If anybody is preaching to you a gospel other than what you accepted, let them be under God’s curse!
2 Corinthians 11:4 For if someone comes to you and preaches a Jesus other than the Jesus we preached, or if you receive a different spirit from the Spirit you received, or a different gospel from the one you accepted, you put up with it easily enough.
2 Corinthians 11:13 For such people are false apostles, deceitful workers, masquerading as apostles of Christ. 14 And no wonder, for Satan himself masquerades as an angel of light. 15 It is not surprising, then, if his servants also masquerade as servants of righteousness. Their end will be what their actions deserve.
Acts 20:29 I know that after I leave, savage wolves will come in among you and will not spare the flock.
And Peter warns us---
2 Peter 2:1-3 But there were also false prophets among the people, just as there will be false teachers among you. They will secretly introduce destructive heresies, even denying the sovereign Lord who bought them—bringing swift destruction on themselves. 2 Many will follow their depraved conduct and will bring the way of truth into disrepute. 3 In their greed these teachers will exploit you with fabricated stories. Their condemnation has long been hanging over them, and their destruction has not been sleeping