What do you know about the religious condemnation of homosexuality?

In my human sexuality class today, we were talking about religious condemnation of homosexuality, namely Christianity and Judaism. My professor pointed out that maybe one of the reasons Christianity condemns homosexuality is because, originally, it was a way to further squeeze out the pagans. I have also heard that homosexuality is actively condemned in the bible. Does anyone know the passages that condemn homosexuality?

My professor also spoke about Judaism and he thinks that when Judaism came about, it did not condemn homosexuality but extra-marital sex and homosexuality tended to fall under this broader category. What does the collective know and/or think of this?