How should a Christian respond to heretics, false teaches, those who promote unbiblical and divisive doctrines, who seek to upset the peace and unity of the church, who teach contrary to the faith once delivered to the saints, misrepresent the gospel, redefine the grace or God or who have a fleshly craving for controversy?
The Bible is clear:
I appeal to you, brothers, to watch out for those who cause divisions and create obstacles contrary to the doctrine that you have been taught; avoid them. For such persons do not serve our Lord Christ, but their own appetites, and by smooth talk and flattery they deceive the hearts of the naive. ~ Romans 16:17-18
If anyone teaches a different doctrine and does not agree with the sound words of our Lord Jesus Christ and the teaching that accords with godliness, he is puffed up with conceit and understands nothing. He has an unhealthy craving for controversy and for quarrels about words, which produce envy, dissension, slander, evil suspicions, and constant friction among people who are depraved in mind and deprived of the truth, imagining that godliness is a means of gain. ~ 1 Timothy 6:3-5
As for a person who stirs up division, after warning him once and then twice, have nothing more to do with him, knowing that such a person is warped and sinful; he is self-condemned. ~ Titus 3:10-11