Heresy

One of the tasks of apologetics - the branch of theology concerned with the intelligent presentation and defense of the historical Christian faith - is to counter heresy (the opposite of orthodoxy) with sound doctrine.

Heresy is:

doctrine which is erroneous in such a way that Christians must divide themselves as a church from all who teach or accept it; those adhering to heresy are assumed to be lost, although Christians are unable to make definitive judgments on this matter. The opposite of orthodoxy. Adj.: “heretical.”

- Source: A Biblical Guide To Orthodoxy And Heresy, Christian Research Journal, Summer 1990, by Robert M. Bowman.

The entry addresses heresy from a Christian perspective. However, the term is used in other religions as well.

Easton’s Bible Dictionary says ‘heresy’ is derived from…

…a Greek word signifying (1) a choice, (2) the opinion chosen, and (3) the sect holding the opinion. In the Acts of the Apostles (5:17; 15:5; 24:5, 14; 26:5) it denotes a sect, without reference to its character.

Elsewhere, however, in the New Testament it has a different meaning attached to it. Paul ranks “heresies” with crimes and seditions (Gal. 5:20). This word also denotes divisions or schisms in the church (1 Cor. 11:19).

In Titus 3:10 a “heretical person” is one who follows his own self-willed “questions,” and who is to be avoided. Heresies thus came to signify self-chosen doctrines not emanating from God (2 Pet. 2:1).
- Source: Heresy , Easton Bible Dictionary

A person who teaches heresy is called a heretic. A church, movement or organization that claims to be Christian, but which nevertheless teaches heresy, is a cult of Christianity. Christians who have not learned discernment easily fall prey to such groups.

Heresy vs. the Essential Doctrines of the Christian Faith

Charges of heresy are most serious where they involve deviation from - or denial of - the central, essential doctrines of Christianity:

a. "Central doctrines" of the Christian faith are those doctrines that make the Christian faith Christian and not something else.

1. The meaning of the expression "Christian faith" is not like a wax nose, which can be twisted to mean whatever the speaker wants it to mean.

2. The Christian faith is a definite system of beliefs with definite content (Jude 3)

3. Certain Christian doctrines constitute the core of the faith. Central doctrines include the Trinity, the deity of Christ, the bodily resurrection, the atoning work of Christ on the cross, and salvation by grace through faith. These doctrines so comprise the essence of the Christian faith that to remove any of them is to make the belief system non-Christian.

4. Scripture teaches that the beliefs mentioned above are of central importance (e.g., Matt. 28:19; John 8:24; 1 Cor. 15; Eph. 2:8-10).

5. Because these central doctrines define the character of Christianity, one cannot be saved and deny these.

6. Central doctrines should not be confused with peripheral issues, about which Christians may legitimately disagree.
Peripheral (i.e. non-essential) doctrines include such issues as the timing of the tribulation, the method of baptism, or the structure of church government. For example, one can be wrong about the identity of "the spirits in prison" (1 Peter 3:19) or about the timing of the rapture and still go to heaven, but one cannot deny salvation by grace or the deity of Christ (John 8:24) and be saved.

7. Christian denominations — whether Roman Catholic, Eastern Orthodox, or Protestant — agree on the essential core. The relatively minor disagreements between genuinely Christian denominations, then, cannot be used to argue that there is no objectively recognized core of fundamental doctrine, which constitutes the Christian faith.
- Source: Alan Gomes, Unmasking the Cults

Unpopular Subject

In todays “that’s true for you, but not for me” society identifying heresy - a process that necessarily involves discernment and judgment - is unpopular, and yet necessary:

Within late twentieth-century North American Christianity, heresy has become an unpopular word. Can’t we all just get along and live together in peace? Unfortunately the answer is no. Peace cannot be purchased at the expense of truth. In 1 Timothy, Paul writes that we are to pay close attention to ourselves and the doctrine and to continue in it, for in doing so we shall save both ourselves and those who hear us (1 Tim. 4:16). There is an inviolable core to the Christian faith. Harsh as it sounds, to violate that core is to place ourselves outside the Christian tradition. This is the essence of heresy, and heresy remains a valid category for today. This is not to endorse a McCarthyism that finds heretics under every rock. Nor is it to end the action of God’s grace in anyone’s life. But it is to own up to the fact that truth is never supplemental but always fundamental to Christian community.

- Source: William A. Dembski, The Task of Apologetics, in Unapologetic Apologetics, edited by William A. Dembski and Jay Wesley Richards, InterVarsity Press, Downers Grove, Illinois, 2001. Page 43.

http://www.apologeticsindex.org/447-heresy-heretic