There seems to be quite a bit of labeling of people as heretics in recent years. It is easy to discount people with a label, but have people really thought through what this means? The word heretic or heresy does not technically mean something bad or even false. It literally means sect, opinion or sentiment. Here are a couple of passages where outsiders described the early Christians as a sect.
“For we have found this man a plague, one who stirs up riots among all the Jews throughout the world and is a ringleader of the sect of the Nazarenes. But this I confess to you, that according to the Way, which they call a sect, I worship the God of our fathers, believing everything laid down by the Law and written in the Prophets, But we desire to hear from you what your views are, for with regard to this sect we know that everywhere it is spoken against.” (Acts 24:5, 14; 28:22 ESV)
The word translated ‘sect’ is the Greek word from which we get heresy. While they may have been using this in a pejorative sense, they were actually correct: Christianity began as a sect or heresy of Judaism. In this way, Roman Catholics are correct to see protestants as a heresy. I just happen to believe that this heresy is more biblically correct than its parent group.
Well, what do we mean we speak of a Christian heresy? It is very easy to describe positions that people disagree with as heresies, and by that they mean something un-Christian or unorthodox. But where do we draw the line? Should Calvinists see Arminians as heretics and Arminians see Calvinists as heretics? How should evangelicals see Pentecostals or people who baptize infants see people who baptize believers? How about amillennialists and postmillennialists and premillennialists?
That is not to say that we should not draw a line. There is a difference between biblical Christianity and unorthodox belief systems. I would make this suggestion of doctrines that must be present to be orthodox:
1) God as personal, separate from creation, omniscient, omnipotent, omnipresent and triune.
2) Jesus as historical, God incarnate, crucified, atoning and resurrected.
3) Salvation by grace through faith, found only through the atoning sacrifice of Jesus on the cross.
We may disagree on other things, but I would hesitate to label a person or movement as heretical if they agreed on these doctrines.