heretic

One who, having professed the faith of Christ, corrupts its dogmas. He may be a material heretic, adhering to heresy innocently or from involuntary causes, or a formal heretic, knowingly and freely adhering to heresy.

One who holds opinions at variance with recognized teachings in philosophy, science, or art.

Since the term is somewhat odious, it is more properly applied to the originators of heresy than to their descendants and remote followers.