"I am amazed that you are so quickly deserting Him who called you by the grace of Christ, for a different gospel; which is really not another; only there are some who are disturbing you and want to distort the gospel of Christ. But even if we, or an angel from heaven, should preach to you a gospel contrary to what we have preached to you, he is to be accursed! As we have said before, so I say again now, if any man is preaching to you a gospel contrary to what you received, he is to be accursed! For am I now seeking the favor of men, or of God? Or am I striving to please men? If I were still trying to please men, I would not be a bond-servant of Christ." (Galatians 1:6-10)There are two broad categories of heresy, those that are "Gospel minus" and those that are "Gospel plus." In the case of the Galatian church, they were facing a "Gospel plus" challenge. There were those who came to them seeking to add onto the Gospel already preached to them by Paul. theirs was a Gospel of faith plus Law. They sought to bring the Galatian church back into obedience to the Jewish law, including circumcision, dietary requirements, and the keeping of certain feasts and days. Christ was fine, but these other things were still necessary for their salvation. The heretics don't care so much what we believe as long as, at the end of the day, we agree with them. Let them believe in Christ as long as they still keep the Law and the requirements of men. Paul calls such additions to the Gospel distortions, perversions, and corruptions of the truth and their purveyors as agitators or, literally, those who "stir the waters."
The goal of the Gospel is our liberty; to free us from sin and the present evil age, and to deliver us to the freedom of righteousness and the kingdom of love. However, the goal of all heresy is bondage; bondage to a teaching and, most often, also to a teacher. Heresy forces conformance; it states that "apart from us there is no salvation." The true gospel releases us from the bondage of men and states, "apart from Christ there is no salvation." You can know salvation without becoming conformed to the image and wishes of some man or group of people. To those who seek to enslave us and to "evangelize" us to some other Gospel, Paul says, "let them be anathematized!"
The Gospel has been "once for all handed down to the saints." (Jude 3) It is now our responsibility to maintain what we have received; to guard it from additions or subtractions, to guard it from corruptions and mutations. Our faith should be so situated in the Gospel of Christ that, even if Paul or an angle should come to us and preach some other sort of Gospel, that we would not heed them nor surrender up to them and their deception what we have already received. There are things worth holding on to, there are things worth defending and protecting, and the Gospel is one of those things.
In the end, such a position may not serve to conciliate men nor ingratiate us towards them. There will always be those who will seek our acceptance of them and our obedience to their message. They may even be offended at the apparent stubbornness of our faith and our refusal to follow them. However, the fragile egos of such heretics are not our concern. To us belong the truth of God and the call to hold fast to what we have already received. Stand fast in the truth and surrender it to no one. It is more precious than gold!