2 John 1:10

he that abideth in the doctrine of Christ, he hath both the Father and the Son. If any come to you, and bring not this doctrine,

Titus 3:10

An heretic after a first and second admonition reject,

Galatians 1:8-9

But if we or an angel from heaven preach to you another gospel than we have preached to you, let him be accursed:

Romans 16:17-18

Now I beseech you, brethren, mark them who cause divisions and offences, contrary to the doctrine which ye have learned, and avoid them.

But I have now written unto you, if any who is named a brother, be a lewd person, or covetous, or an idolater, or a railer, or a drunkard, or rapacious, not to converse with such an one, no, not to eat with him.

2 Thessalonians 3:6

Now we command you, brethren, in the name of our Lord Jesus Christ, to withdraw yourselves from every brother that walketh disorderly and not according to the tradition which he received of us.