Ah. There you hit the nail on the head. Homosexuals, in order to reproduce, must engage in Heterosexual relations. So...which is more natural? Heterosexual relations can sustain themselves. Homosexual ones cannot, without also utilizing heterosexual relations. Homosexuality depends on there still being Heterosexuals out there in order to survive.
My good friend, YOU are the product of heterosexual activity: an egg and a sperm cell. Homosexuals can reproduce, yes...but only by artificial means. Key word there: Artificial. Not natural.
Yes, I've seen two male sheep going at it. You know why? Because there weren't any female sheep around; the two sheep were raised for food, and they (unfortunately) weren't castrated. The sight was...disturbing. Yes, it's unnatural. And disgusting. So aren't we better than animals? You're advocating behaving like animals. Well, if you ever get out in nature and actually watch what happens, nature is a pretty nasty place! Animals kill each other to survive, for food, whatever. Sometimes just because they can. If we are to behave like animals, then yes, homosexuality is fine. But so is cannibalism and murder. And incest. And just about anything else under the sun.
Why would a homosexual be detrimental to evolution? Lol...they wouldn't; if they engaged only in homosexual activity from birth to death, they would breed themselves out of existence in one lifetime. You're speaking of individuals, not as a group. So what if some homosexual dude has great genetics from a physical standpoint? In order to pass those on, they've still got to engage in heterosexual relations at some point. As a group, homosexuals do not benefit Evolution as a whole, nor will they survive more than one lifetime...UNLESS THEY ALSO ENGAGE IN HETEROSEXUAL RELATIONS. Wow. Imagine that.
I will also note that I am only arguing from this viewpoint because you wouldn't accept any Christian argument I could offer. Which, I am a Christian. I believe in Jesus Christ as my lord and savior. Evolution? Well, yes and no; Microevolution, yes. Evolution within a species does take place, and is the reason why there are thousands of dog breeds out there today and not just one. Macroevolution, now, the idea that a dog can evolve into a human given enough time, that concept is laughable. Because, the only instances that support Macroevolution to some degree do an even better job supporting Creationism. Continued...