Possible reasons: (Which also apply to casual heterosexual activity)
Creatures seeking perfection in other creatures, which is a form of creature worship rather than consummate oneness.
Humans are expected to strive for better and more noble things in life than the perfect orgasm.
I can't think of any more reasons without citing religious dogma. I digress for now and can only say that Homosexual behavior could be done better. (A Higher and more noble purpose)
If sex is not being used for procreation, what difference is it from mutual masturbation?
Re: It;s oxymoronic to use High&Nobel and Homosexual in the same breath
StElsewhere writes:
What could ever be "High and Nobel" about something that is an abomination in the eyes of the True and Living God?
My whole point is that same gender attraction need not be expressed on a sexual level. There may well be a higher and nobler purpose for the attraaction than sex. There is nothing immoral about attraction...only motives and actions(behaviors)