Because Christianity feels that all sex is sinful. Celibacy, according to the Bible, is the preferred lifestyle. Hetero sex is required to procreate, so they couldn't ban it completely the way they have with gay sex.
Atheist Forums Hall of Shame:
"The trinity can be equated to having your cake and eating it too."
... -Lucent, trying to defend the Trinity concept
"(Yahweh's) actions are good because (Yahweh) is the ultimate standard of goodness. That’s not begging the question"
... -Statler Waldorf, Christian apologist
"The trinity can be equated to having your cake and eating it too."
... -Lucent, trying to defend the Trinity concept
"(Yahweh's) actions are good because (Yahweh) is the ultimate standard of goodness. That’s not begging the question"
... -Statler Waldorf, Christian apologist