Genesis 19:1-11
In story of Sodom, two angels are guests in Lot's home, and all the men surround the house and demand that Lot bring out the two men, "that we may know them." Lot offers to them his two virgin daughters instead, saying, "Do nothing to these men, for they have come under the shelter of my roof." The men of Sodom start to break down the door, and the two angels pull Lot back inside, and strike the men outside blind. Then God pops a cap in their ass, and destroys Sodom, yada yada yada... The misunderstanding is what the sin being professed here actually is.
Their sin is the attempted gang rape of Lot's male guests. That they are all male is inconsequential. The gang rape of a woman by men doesn't mean that all heterosexual behavior is wrong. For the same reason, gang rape of a man by other men doesn't mean that all homosexual behavior is wrong. What's wrong is the rape. A story with a similar message, which also refutes the idea that homosexuality is inherently wrong, is in Judges 19. In this story, a group of men attempts to gang rape other men, but this time, when a woman is offered as a substitute, she is gang raped and killed.
There's actually another sin in this story, although it's less relevant in modern times. In Lot's time, when you provided hospitality to someone, especially in the desert, you were giving them sanctuary because being exposed to those conditions too long would be certain death. To provide hospitality to the two angels was a very important duty, and to allow them to be dishonored, as the group of men would have, would have been a gross violation of his sacred duty.
Jude 7 and 2 Peter 2:4-10 refers to Sodom, too. Jude speaks of those who "indulged in sexual immorality and pursued unnatural lust." In the New Revised Standard Version, a footnote says the literal Greek is, "went after other flesh". Peter uses the phrases "depraved lust," or "unlawful acts." These references to Sodom are sexual in nature, but they are applicable to the sinful, immoral, and unethical capabilities of all. According to scholars the phrase, "went after other flesh," probably refers to Lot's guests, who are angels disguised as men.
By the way, in the King James Version of the Bible, the word 'sodomite' is used incorrectly. The New Revised Standard Version has a more accurate translation saying, "None of the daughters of Israel shall be a temple prostitute; none of the sons of Israel shall be a temple prostitute. You shall not bring the fee of a prostitute or the wages of a male prostitute into the house of the Lord your God." In Hebrew the word translated as "sodomite" in the King James Version actually means "male temple prostitute."