But [in those days] false prophets arose among the people, just as there will be false teachers among you, who will subtly introduce destructive heresies, even denying the Master who bought them, bringing swift destruction on themselves.

After

“If your brother sins, go and show him his fault in private; if he listens and pays attention to you, you have won back your brother.

I have already warned those who have sinned in the past and all the rest as well, and I warn them now even though I am absent [from you] as I did when I was with you the second time, that if I come back I will not spare anyone,

Reject

I urge you, brothers and sisters, to keep your eyes on those who cause dissensions and create obstacles or introduce temptations [for others] to commit sin, [acting in ways] contrary to the doctrine which you have learned. Turn away from them.

In the name of our Lord Jesus, when you are assembled, and I am with you in spirit, with the power of our Lord Jesus,

I wish that those who are troubling you [by teaching that circumcision is necessary for salvation] would even [go all the way and] castrate themselves!

Now we command you, believers, in the name of our Lord Jesus Christ and by His authority, that you withdraw and keep away from every brother or sister who leads an undisciplined life and does not live in accordance with the tradition and teaching that you have received from us.

holding to a form of [outward] godliness (religion), although they have denied its power [for their conduct nullifies their claim of faith]. Avoid such people and keep far away from them.

If anyone comes to you and does not bring this teaching [but diminishes or adds to the doctrine of Christ], do not receive or welcome him into your house, and do not give him a greeting or any encouragement;