Is there anyone who thinks homosexuality is wrong for something other than religious reasons?

Religion may be one reason, but some of the most prominent anti-gay crusaders, were never religious. J. Edgar Hoover, Roy Cohen to name but a couple. Interestingly enough, they were both closeted homosexuals.

For some, it's about going against the "natural order" of things.

There's no point in raising the evolutionary flag. If someone truly believes in that, then sex would only happen for procreation purposes, and we know this is not true.