Heresy; Heretic

Concise Bible Dictionary:

The word αἴρεσις is from “to choose.” The same Greek word is translated “sect” and is applied to the sects among the Jews, as the Sadducees and the Pharisees (Acts 5:1717Then the high priest rose up, and all they that were with him, (which is the sect of the Sadducees,) and were filled with indignation, (Acts 5:17); Acts 15:55But there rose up certain of the sect of the Pharisees which believed, saying, That it was needful to circumcise them, and to command them to keep the law of Moses. (Acts 15:5); Acts 26:55Which knew me from the beginning, if they would testify, that after the most straitest sect of our religion I lived a Pharisee. (Acts 26:5)). It was employed by the Jews respecting Christianity (Acts 24:5,145For we have found this man a pestilent fellow, and a mover of sedition among all the Jews throughout the world, and a ringleader of the sect of the Nazarenes: (Acts 24:5)
14But this I confess unto thee, that after the way which they call heresy, so worship I the God of my fathers, believing all things which are written in the law and in the prophets: (Acts 24:14); Acts 28:2222But we desire to hear of thee what thou thinkest: for as concerning this sect, we know that every where it is spoken against. (Acts 28:22)). Heresies and sects were developed early in the church, they were the result of the working of the will of man in some form. The root of the Greek word being “to choose” shows that a heresy is something peculiar. The doctrine held and enforced may be true in itself but may be exaggerated or put out of its connection. The common result is, a party or sect is formed (1 Cor. 11:1919For there must be also heresies among you, that they which are approved may be made manifest among you. (1 Corinthians 11:19); Gal. 5:2020Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies, (Galatians 5:20); 2 Pet. 2:11But 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 bought them, and bring upon themselves swift destruction. (2 Peter 2:1)). One who adheres to a heresy is a heretic, and after the first and second admonition is to be rejected (Titus 3:1010A man that is an heretick after the first and second admonition reject; (Titus 3:10)). God having given in His word all things needed for the church, there is no room for man’s choice or man’s will: he must be a humble receiver (compare 1 Cor. 4:77For who maketh thee to differ from another? and what hast thou that thou didst not receive? now if thou didst receive it, why dost thou glory, as if thou hadst not received it? (1 Corinthians 4:7)).

From Anstey’s Doctrinal Definitions:

This refers to an outward division in the Christian testimony, wherein a party separates itself as a distinct company. “Heresy” is the making of a “sect” among Christians and is translated as such in 1 Corinthians 11:1919For there must be also heresies among you, that they which are approved may be made manifest among you. (1 Corinthians 11:19) in the J. N. Darby Translation. It is an evil that emanates from the flesh—the fallen sin-nature (Gal. 5:2020Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies, (Galatians 5:20)). In Scripture, it is applied to divisions that had developed in the Jew’s religion (Acts 5:17; 15:5; 24:5; 26:517Then the high priest rose up, and all they that were with him, (which is the sect of the Sadducees,) and were filled with indignation, (Acts 5:17)
5But there rose up certain of the sect of the Pharisees which believed, saying, That it was needful to circumcise them, and to command them to keep the law of Moses. (Acts 15:5)
5For we have found this man a pestilent fellow, and a mover of sedition among all the Jews throughout the world, and a ringleader of the sect of the Nazarenes: (Acts 24:5)
5Which knew me from the beginning, if they would testify, that after the most straitest sect of our religion I lived a Pharisee. (Acts 26:5)) and divisions that would develop in Christianity (1 Cor. 11:1919For there must be also heresies among you, that they which are approved may be made manifest among you. (1 Corinthians 11:19); Gal. 5:2020Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies, (Galatians 5:20); 2 Peter 2:11But 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 bought them, and bring upon themselves swift destruction. (2 Peter 2:1)).
Heresy is not the same as a “schism,” which is an inward split or rift among Christians (1 Cor. 11:1818For first of all, when ye come together in the church, I hear that there be divisions among you; and I partly believe it. (1 Corinthians 11:18) – marginal reading in the KJV). Those involved in a schism will still meet outwardly with those with whom they differ, but probably unhappily (Rom. 16:1717Now I beseech you, brethren, mark them which cause divisions and offences contrary to the doctrine which ye have learned; and avoid them. (Romans 16:17); 1 Cor. 1:10; 3:3; 11:1810Now I beseech you, brethren, by the name of our Lord Jesus Christ, that ye all speak the same thing, and that there be no divisions among you; but that ye be perfectly joined together in the same mind and in the same judgment. (1 Corinthians 1:10)
3For ye are yet carnal: for whereas there is among you envying, and strife, and divisions, are ye not carnal, and walk as men? (1 Corinthians 3:3)
18For first of all, when ye come together in the church, I hear that there be divisions among you; and I partly believe it. (1 Corinthians 11:18)). This was the case with the Corinthians. The Apostle Paul warned them that if schisms existed, and were not dealt with and judged as evil, “there must also be heresies” that would grow out of those schisms (1 Cor. 11:18-1918For first of all, when ye come together in the church, I hear that there be divisions among you; and I partly believe it. 19For there must be also heresies among you, that they which are approved may be made manifest among you. (1 Corinthians 11:18‑19)). Hence, an inward split (a schism) will develop into an outward split (a heresy), given enough time. A person who engineers an outward split among Christians is a “heretic” (Titus 3:1010A man that is an heretick after the first and second admonition reject; (Titus 3:10)). Paul tells us that if we meet such a person who has gone out in self-will with his party, we are to, “after a first and second admonition, have done with him” (Titus 3:1010A man that is an heretick after the first and second admonition reject; (Titus 3:10)).
Heresy is commonly thought to be bad doctrine, and was popularized as such by the Roman Catholic Church hundreds of years ago. They labeled everyone who would not uphold their doctrines as heretics. Bible teachers today sometimes use the term conventionally to indicate doctrinal error, but heresy, as to its Scriptural meaning, does not necessarily involve bad doctrine at all. G. V. Wigram tells us that the worst and most difficult kind of heresy to detect is that which does not involve bad doctrine, yet the spirit of party-making and division are there (Memorials of the Ministry of G. V. Wigram, vol. 2, p. 91). Heresy has probably become synonymous with bad doctrine because most heretics usually form their division around bad doctrine (2 Peter 2:11But 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 bought them, and bring upon themselves swift destruction. (2 Peter 2:1)).
Thus, a heresy/sect is the forming of a fellowship of believers outside of, and separate from, the one fellowship to which all Christians have been called in Scripture—which “the Lord’s Table” symbolizes (1 Cor. 1:9; 10:219God is faithful, by whom ye were called unto the fellowship of his Son Jesus Christ our Lord. (1 Corinthians 1:9)
21Ye cannot drink the cup of the Lord, and the cup of devils: ye cannot be partakers of the Lord's table, and of the table of devils. (1 Corinthians 10:21)). The evil of heresy is that it divides the Christian testimony into separate groups and fellowships, each with their own administration, by-laws, etc. It is not God’s will to have Christians divided like this. He would have them to meet together on one ground of fellowship (even though they may be in various localities all over the world), so as to give expression to the fact that they are “one body” (Eph. 4:44There is one body, and one Spirit, even as ye are called in one hope of your calling; (Ephesians 4:4)). The making of all such churches in Christendom (“church planting” as it is called) is usually done with good intentions but in ignorance of God’s way of gathering Christians together for worship and ministry. We, therefore, need to show much patience with those who are in these man-made fellowships. Nevertheless, all such church making efforts destroy the unity of the body in practise.