What's a heresy?

Someone recently asked what a heresy was. Here is my answer.
______________________
1. First, heresy has to do with the beliefs of our head. In that sense:

• Heresy is not about ethics. The Church in its earliest centuries did not largely fight over ethics but over beliefs. In that sense, it can be wrong do do something but it is not heresy to do something.
• Heresy is not about salvation. God judges us according to our "heart," that is, our faith in him. Our decisions and actions flow from our heart toward God. Out of the heart thus comes forth sin and death. God does not judge us according to our beliefs except insofar as our beliefs are an expression of our hearts. This is the direction with which God is ultimately concerned--heart to action, heart to belief (not belief to action, not action in itself).

2. Heresy, properly so called, has to do with deviance from the ecumenical creeds (and thus dogmas) of Christendom.

• Deviation with regard to the Trinity.
• Deviation with regard to the resurrection.
• Note that such heresies only became heresies after the ecumenical councils that finally brought those debates to conclusion. The author of Ecclesiastes was not a heretic for not understanding the fullness of life after death. Arius was not a heretic until after 381, after his death, when the Nicene Creed was finalized.

3. There are informal heresies, which approach heresies because they relate to the general consensus of the church (and thus to doctrines) but which are not addressed in the creeds.

•  Open theism denies the absolute foreknowledge of God. This a "heresy light" because Christians everywhere have long affirmed the full foreknowledge of God. But the issue is not addressed in the creeds.
• The inspiration of Scripture is the common belief of Christendom, but it has never been affirmed in an ecumenical creed nor has its precise nature ever been spelled out by the Church at large.
• The belief that homosexual practice is acceptable in a monogamous relationship falls outside the consensus of Christianity throughout the ages. While the practice is a question of orthopraxy rather than orthodoxy, the belief stands outside the consensus of the Church.

4. Deviation from the particular beliefs of one's church or one's tradition stands outside debates over heresy, although it does relate to one's participation in a particular Christian community.

• One's position on the nature of predestination, individual will, or eternal security
• One's position on particular atonement theories or a teaching like eternal security.
• One's position on the inerrancy of Scripture

5. There is a host of issues where one may have Christian convictions on an issue. This is where you believe God has bound you to a particular perspective and practice, but you do not see them as binding on others.