The basis for morality is this: "If everyone else in the entire world were to do this, would it be good for society?" That being said Gay relationships cannot naturally lead to offspring (a petri dish is not natural). If everyone in the whole world was to turn homosexual then that would be the end of the human race through natural reproduction. That sure doesn't sound moral to me. We can apply the same test to murder, abusing drugs, stealing/lying, sex with animals, etc. Basically Homosexuality is just as immoral as murder, you can't beat that logic.