A heresy is a belief that deviates from some standard, official belief. When religious authorities decide that a belief is heretical, they usually take active efforts to eradicate the belief, usually including the removal of the offending believers (by excommunication or worse). Of course, one man's orthodoxy is another man's heresy!
Most Christian heresies centered around the twin issues of the nature of the trinity and more specifically, the nature of Jesus Christ. The official stand on these issues according to the Roman Catholic Church is as follows: God is a trinity, three persons but one essence; Jesus Christ was one person, simultaneously human and divine. That these two statements are not particularly rational was considered irrelevant. The trinity was seen as mysterious and a matter of faith, not reason.
The word heresy comes from haeresis, a Latin transliteration of the Greek word meaning choosing, choice, course of action, or in an extended sense sc
HERESY: TOWARD A DEFINITION
The word appears in the New Testament and was appropriated by the Catholic Church to mean a sect or belief that threatened the unity of Christian doctrine. Heresy is frequently regarded as a departure from orthodoxy.
Heresy is an emotionally loaded term that is often misused. It is not the same thing as incredulity, schism, apostasy, or other sins against faith. The Catechism of the Catholic Church states, "Incredulity is the neglect of revealed truth or the willful refusal to assent to it. Heresy is the obstinate post-baptismal denial of some truth which must be believed with divine and Catholic faith, or it is likewise an obstinate doubt concerning the same; apostasy is the total repudiation of the Christian faith; schism is the refusal of submission to the Roman Pontiff or of communion with the members of the Church subject to him" (CCC 2089).
To commit heresy, one must refuse to be corrected. A person who is ready to be corrected or who is unaware that what he has been saying is against Church teaching is not a heretic.
A person must be baptized to commit heresy. This means that movements that have split off from or been influenced by Christianity, but that do not practice baptism (or do not practice valid baptism), are not heresies, but separate religions. Examples include Muslims, who do not practice baptism, and Jehovah’s Witnesses, who do not practice valid baptism.
Finally, the doubt or denial involved in heresy must concern a matter that has been revealed by God and solemnly defined by the Church (for example, the Trinity, the Incarnation, the Real Presence of Christ in the Eucharist, the sacrifice of the Mass, the pope’s infallibility, or the Immaculate Conception and Assumption of Mary).
It is important to distinguish heresy from schism and apostasy. In schism, one separates from the Catholic Church without repudiating a defined doctrine. An example of a contemporary schism is the Society of St. Pius X—the "Lefebvrists" or followers of the late Archbishop Marcel Lefebvre—who separated from the Church in the late 1980s, but who have not denied Catholic doctrines. In apostasy, one totally repudiates the Christian faith and no longer even claims to be a Christian.
With this in mind, let’s look at some of the major heresies in the Church’s history.
HERESIES OF THE EARLY CHURCH
The major heresies fall into three categories: heresies of the nature of Christ; heresies of the Trinity; and heresies of man and salvation.
HERESIES OF CHRIST
The orthodox idea of Christ was that he is fully God, yet existed as fully human, the two natures being “eternally distinct and uniquely united” at the same time, and that he suffered as a human.
Named after Apollinarius, belief that Christ had no soul, but rather was filled with logos, or the Word,...