I don't see much controversial about the biblical doctrine to beware of false teachers who preach false doctrine. It is part of basic Christian theology 101. It is a theme which appears in just about every NT book except Phileamon and is the major theme of Galatians, 1 John and Jude. 2 Timothy also devotes a substantial amount of text to it.
You can see in this thread what happens when religious deception in Christianity is brought up....yet you're right...there IS a false Christianity..
2Co 11:13 For such are false apostles, deceitful workers, transforming themselves into apostles of Christ.
2Co 11:14 And no wonder! For Satan himself transforms himself into an angel of light.
2Co 11:15 Therefore it is no great thing if his ministers also transform themselves into ministers of righteousness, whose end will be according to their works.
Their "works" are works of lawlessness. Homosexaul ordinations. Acceptance of sin. Teaching people to break God's commandments...all in the name of love and tolerance...