Why do religious people not approve of homosexuality?

[fredv3b]

The clans which accepted homosexuality would've been more likely to die out in the future because they inevitably produced less offspring.

I am sorry but I disagree. While what you say might be true of female homosexuality, I believe it is false with respect to male homosexuality. Primitive tribes had no shortage of men to father children, one man can father children by many women. Men of high social status often take more than one wife, men of low social status may be unable to find a wife. The offspring not sired by a few gay men would easily be sired by others. So long as those few gay men were economically productive and supported their young siblings and nieces and nephews then there is no reason to believe that an accepting tribe would fail to survive. Especially when you appreciate that most children born would not live to sexual maturity, feeding children better may be a superior reproductive strategy than having more children.