αἵρεσις

And indeed, there must be differences among you to show which of you are approved.

Now there were also false prophets among the people, just as there will be false teachers among you. They will secretly introduce destructive heresies, even denying the Master who bought them—bringing swift destruction on themselves.

But some believers from the party of the Pharisees stood up and declared, “The Gentiles must be circumcised and required to obey the law of Moses.”

We have found this man to be a pestilence, stirring up dissension among the Jews all over the world. He is a ringleader of the sect of the Nazarenes,

I do confess to you, however, that I worship the God of our fathers according to the Way, which they call a sect. I believe everything that is laid down by the Law and written in the Prophets,