I reckon many a men have become weak in their calling out of false teachers and their heresy:
Paul called false teachers: “dogs” and “evil workers”. He used the “Beware” word like we use it for “BEWARE OF DOG”.
Philippians 3:2 Beware of dogs, beware of evil workers, beware of the concision.
Those who pervert or preach another gospel of Christ Paul said “Let them be accursed”:
Galatians 1:7-9 Which is not another; but there be some that trouble you, and would pervert the gospel of Christ. But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed. As we said before, so say I now again, If any man preach any other gospel unto you than that ye have received, let him be accursed.
Paul called them “evil men and seducers” and “deceiving” and did not say they would get better but worse and worse:
2 Timothy 3:13 But evil men and seducers shall wax worse and worse, deceiving, and being deceived.
He called false teachers “men of corrupt minds, reprobate concerning the faith”:
2 Timothy 3:8 Now as Jannes and Jambres withstood Moses, so do these also resist the truth: men of corrupt minds, reprobate concerning the faith.
He called them “false apostles, deceitful workers”:
2 Corinthians 11:13 For such are false apostles, deceitful workers, transforming themselves into the apostles of Christ.
Here Paul holds nothing back:
Acts 13:10 And said, O full of all subtilty and all mischief, thou child of the devil, thou enemy of all righteousness, wilt thou not cease to pervert the right ways of the Lord?
He warned of “grievous wolves”
Acts 20:29 For I know this, that after my departing shall grievous wolves enter in among you, not sparing the flock.
He labeled false teachings as “doctrines of devils”
1 Timothy 4:1 Now the Spirit speaketh expressly, that in the latter times some shall depart from the faith, giving heed to seducing spirits, and doctrines of devils;