Heresies don’t get a lot of attention these days and the more I visit churches within the different denominations of Christianity, the more that I hear heresies being preached. Having a love for church history, this is somewhat disturbing. Because of this, I have decided to do a series on the Christian heresies. The first set of posts will deal with the Christological heresies: Arianism, Docetism, Nestorianism, Adpotionism, Eutychianism, and Theopaschitism. The second set of posts will deal with the heresies of the church and Christian living: Marcionism, Donatism, Pelagianism, Gnosticism, and the heresy of the Free Spirit.
Before we look at the different heresies, one must know what a heresy is.
Heresy vs. Orthodoxy
Heresy comes from the Greek αιρεσεις (hairesis) originally meant party, sect, faction, or choice. Early in the history of Christianity, heresy came to “mean a separation or split resulting from a false faith.”  Most heresies in the church threatened the very unity of the church. They “did not refer to simply any doctrinal disagreement, but to something that seemed to undercut the very basis for Christian existence.”  The Gospel itself was at stake.
Orthodox is derived from two Greek words: ορθας (orthas) meaning correct or right and δοξα (doxa) meaning honor. “Orthodox faith and orthodox doctrines are those that honor God rightly, something that ought to be desirable and good.”  It is safe to say that orthodoxy is the truth and that heresies are distortions of the truth. Christianity is an orthodox tradition. But, from time to time, heresies creep up that threaten the very existence of Christianity. The church fights to stay alive and in doing so, further defines the truth.
 Herald O. J. Brown, Heresies, (Garden City: Doubleday & Company, Inc., 1984), 2.
 Ibid., 2.
 Ibid., 1.