A heretic is a person who while a Christian creates controversy, dissension, and division concerning doctrine and belief within the Orthodox Christian church. Such issues arose early in Christ's Church, being noted in a number of the letters of the Apostles, notably in Titus, Timothy, Peter, and John.
As used in Titus, in the New Testament, the word heretic comes from the phrase hairetikon anthropon which is best translated as "one who fosters factions"; that is a person who uses controversy to cause division in the church. Thus, the center of the use of heretic is toward individuals who create factions that espouse an unorthodox idea than to the idea itself, the heresy.
While differences of opinion arise within the church, traditionally these differences are debated and, under God, brought to a common doctrinal and religious understanding by conciliatory means. At times such agreement could not be developed and the parties championing the new ideas, if they continued to press their position, were found to be in heresy and the individuals were declared heretics. Notable examples of heretics during the early centuries during period of the Christological Controversies are Paul of Samosata, Arius and Nestorius.
Among the Apostolic references in the New Testament of incidents of heresy are the following:
Titus 3:9-11 (KJV) 9But avoid foolish questions, and genealogies, and contentions, and strivings about the law; for they are unprofitable and vain. 10A man that is an heretic, after the first and second admonition, reject, 11knowing that he that is such is subverted, and sinneth, being condemned of himself.
2 Peter 2:1-3 (KJV) 1But there were false prophets also among the people, even as there shall be false teachers among you, who privily shall bring in damnable heresies, even denying the Lord that brought them, and bring upon themselves swift destruction. 2And many shall follow their pernicious ways; by reason of whom the way of truth shall be evil spoken of. 3And through covetousness shall they with feigned words make merchandise of you: whose judgment now of a long time lingerth not, and their damnation slumberth not.
1 Timothy 6:3-5 (KJV) 3If any man teach otherwise, and consent not to wholesome words, even the words of our Lord Jesus Christ, and to the doctrine which is according to godliness; 4he is proud, knowing nothing, but doting about questions and strifes of words, whereof cometh envy, strife, railings, evil surmisings, 5perverse disputings of men of corrupt minds, and destitute of the truth, supposing that gain is godliness: from such withdraw thyself.
3 John 9-11 (KJV) 9I wrote unto the church: but Diotrephes, who loveth to have the pre-eminence among them, receiveth us not. 10Wherefore if I come, I will remember his deeds which he doeth, prating against us with malicious words: and not content therewith, neither doeth he himself receive the brethren, and forbiddeth them that would, and casteth them out of the church. 11Beloved, follow not that which is evil, but that which is good. He that doeth good is of God: but he that doeth evil hath not seen God.