Heretic.
Synonyms:
dissenter, heresiarch, non-conformist, schismatic.
Etymologically, a heretic is one who takes or chooses his own belief, instead of the belief of his church; hence, a heretic is one who denies commonly accepted views, or who holds opinions contrary to the recognized standard or tenets of any established religious, philosophical, or other system, school, or party; the religious sense of the word is the predominant one; a schismatic is primarily one who produces a split or rent in the church. A heretic differs in doctrine from the religious body with which he is connected; a schismatic differs in doctrine or practise, or in both. A heretic may be reticent, or even silent; a schismatic introduces divisions. A heresiarch is the author of a heresy or the leader of a heretical party, and is thus at once a heretic and a schismatic. With advancing ideas of religious liberty, the odious sense once attached to these words is largely modified, and heretic is often used playfully. Dissenter and non-conformist are terms specifically applied to English subjects who hold themselves aloof from the Church of England; the former term is extended to non-adherents of the established church in some other countries, as Russia.