I've never understood the double standard. The rules about homosexual behavior are usually right beside the rules about heterosexual behavior, but gays are much more vilified than adulterers or fornicators. Christians aren't allowed to be animals, but have to live according to Christian standards. Most psychiatrists agree that the majority of gays are born that way, while some are turned in that direction by a traumatic childhood. Either way, it's not the person's fault they are gay.
I think the reason most people who are hateful toward homosexuals are because people just tend to be hateful and looking for any excuse to hate. Why do you think it's so easy to stir up entire demographics to hate someone who's DFed, a different color, a different religion, in a different political party, in a different financial situation, etc? Would the Inquisition, the Holocaust, the KKK, the Crusades, any war, any act of terrorism be possible if people weren't prone to hate and violence? These horrible atrocities are/were all committed by normal, everyday people who were given an excuse and an opportunity to act out their natural tendency toward wickedness.
That having been said, the "gay pride" movement is annoying. Okay, it's not your fault you're gay; most rational people get that. But, no, it's not "normal", "natural", or positive in any way. Some people are born with mental disabilities and some others have accidents where they become brain damaged. Either way, the outcome is not something to brag about, have parades to celebrate, or demand other people embrace and want for their own children. Something either went wrong in the womb or during the formative years.
Do you hate someone for being mentally challenged? No. Do you try to work with them and make their life as normal as possible? Yes. Do you wish for them to be made better someday, whether by God or science? Of course. Is their situation going to cause problems and occasional incidents that may be frustrating, awkward, or emotionally painful? Sure. Do you stare at them or harass them for being different? Absolutely not. But let's not swing so far in the other direction that it becomes ridiculous.