For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
There is only one mediator between God and man, Jesus Christ (1 Timothy 2:5.) There is only one flock and one shepherd. (Isaia 55:1-11)
John 10:16 says, "Heaven and Earth shall pass away, but my words shall not pass away." (also Mk 13:31, Lk 21:33)
It's simple.. whatever the false prophets say is contrary to the word. Falsehood doesn't align with the written word of GOD.
All teachers teach at least one principle of holy living in error. Teachers don't get everything right. Teachers understand something pertaining to christian doctrine in error.
"False teachers" INTENTIONALLY teach what is error. They don't want the truth of God, the gospel of Jesus Christ, to be known and believed.
Every teacher and preacher who write on this site get some of this wrong. We believe we know when we don't. But we aren't intentionally misleading people. Yes, there are people who will not repent of their errant beliefs, even after being corrected and realizing they've believed wrongly about a principle or Bible teaching. Stubbornness is why!!
I don't call them false teachers. Most of the commenters on the answer section of this question are torn between the law and the truth. They cling to the law, teaching congregations IN ERROR. I don't call them false teachers; I don't think they know any better.
Martin Luther's revolt against "the church" goes clean over their heads. The law doesn't contain a provision for grace. Grace is void of law. The truth of that means nothing to the teacher or disciple who sees himself as different from the unsaved because of the way he lives. He believes he's saved because he TRIES to live right (obey the law).
Above, I put "the church" in quotations. The church was not intended to be taught to be an organization.That's the reason for the scripture that says 'God does not live in temples made by man' (Acts 17:24).
Therein sits the problem: It's not easy to teach people that sin separates them from God, and in the same breath, teach that Jesus' death and resurrection has removed their sin from their record, and they are now born again because they trust in His sacrifice, even though they continue to break the law that was in place when Jesus was nailed to the cross.
What if you continue to sin the same sin you sinned before you "got saved"? I ask, 'What sin is that? Lying, gossiping, envy, strife, hatred, or does it have to be of a sexual nature'? Does jealousy of another's ministry count? (I hope everyone remembers the right question. It isn't, 'Are you still born again; it's are these sins put on your new record, and do they separate you from God AFTER your new born again life begins? Or do they prove you were never born again')?
That's the dilemma. How can one be saved and continue in sin. (You must say continue IN sin, it makes it sound more intentional than continue TO sin). "In sin" sounds juicy, "to sin" sounds natural. We all know, EVERYBODY sins, but not everybody lives in sin. THEOLOGICAL SEMANTICS!!
So they teach that if you were a tax collector before you met Christ, you must never collect taxes again. If you do you are not saved. They omit the fact that collecting taxes does not keep a person from being a believer. Neither does having sex with people you ain't supposed to have sex with!!
MANY will call this "false teaching." They don't know any better!!