I think the hatred against Homosexuality is more due to modern religions which originated in the Middle East.
The Romans/Greeks and people from the ancient world generally had no issues with it.
If you're a normal dude, and you happen to witness two men barebacking each other, you should experience an immediate onset of undeniably overpowering feelings of disgust and repulsion.
Sexuality is a strong human emotion. It's basically instinct that you can't really control, but only manage. So instead of killing, you just call them fags and evacuate the homosexual crime scene.