On the Proper Orthodox Stance Toward Heresy

A friend wrote the following (to which I respond further down):
"To give away a holy site does not seem right. But a compromise might be to let Roman Catholics uild their own modest chapel on the isle. In many places Orthodox and Catholics must share and ooperate in the Holy Land, especially. At the top of Mt Tabor, for example, is an older Catholic hurch and a newer Orthodox church (and monastery, I believe). Where it is possible, we should be haritable, but not foolishly give away our oil before the Groom comes."
~ It seems to me that your response is very reasonable and quite human and logical. However, it may also be lacking in a true and proper understanding of the catastrophic implications of heresy for the salvation of man and the unity of the Church.
Heresy is so hated by the holy fathers and the Church precisely because it deprives men of the grace of God, that is, of communion with the person of Christ, Who is our salvation. This is so because the grace of God is the spirit of Truth and there is no untruth in Him.
The line that which separates Orthodoxy from heresy is not a line simply between "enlightened" theology and a confused theology, but precisely between Theanthropic existence and merely human existence, between revelation and religion.