What makes you think this verse cannot be more appropriately applied to the false teachers and damnable new false gospel of the reformation?
Posting a proof text does not prove that text was intended the way YOU think it was.
All of Christianity was united in foundational belief till 500 years ago, and there were only two "denominations," if you will, Catholic and Orthodox, and before 1054, there was only Catholicism.
Following on the heels of the reformation was a splintering asunder of Christinity into literally thousands of warring camps, with 99% of protestantism today embracing the contraceptive mentality and teaching their followers that contraception is OK, in absolute and unequivocal violation of all of Christianity's constant teaching on the subject.
Yes indeed, there were false prophets also among the people, even as there shall be false teachers among you, who privily shall bring in damnable heresies, even denying the Lord that bought them, and bring upon themselves swift destruction,
and they exist inside my Church as sinners dissenting from my Church, like the homosexual pedophiles and bishops who hide them, and outside my Church, wherever Christians teach doctrines and morals against that of the Church Christ Himself founded and to which He alone granted authority to teach and to lose and to bind.
I saw this quote the other day and I don't know who said it but it is a good one.