Well, it may not require a religion exactly, but it certainly does require some kind of religious-like dogma to generate the kind of hatred being spewed by the right in the US. And let's face it, in the US at least, it is the religious organizations who are fanatically trying to prevent equality for gays, just as it was the religious organizations (primarily in the South) who fanatically maintained that slavery was sanctioned by God!
It may not require a religion for bigotry, but few things other than religion can inspire that kind of fear and hatred of their own children!