Please tell me that someone will kindly respond to Marni and wiskers.  I am a former evangelical Christian, now an atheist, but support more progressive/open-minded forms of Christianity.  I would love to hear the Bible's explanation for exactly WHY homosexuality is allegedly sinful.  After all, if God exists and the Bible is his word, and science and logic and regard for fellow human beings do not contradict these facts, then one would think there would be a good explanation for why two consenting adults who mutually love and commit themselves to one another is sinful.  I'm sorry, but there just aren't any explanations that cut it.  

The question about child-rearing is a slightly different matter, apart from morality, but still an inadequate reason to keep gay and lesbian folks from being able to marry.  People who are attracted to the opposite sex and want to have kids will continue to do so, even if marriage equality is implemented.  Given the high heterosexual divorce rate, and the massive problems with child abuse, poverty, and other problems that strike gay and straight households alike, wouldn't you say that the most important thing would be for a child to have two parents, if possible, who can assist one another with raising the child, and teach him/her how to cope, adapt, thrive and succeed in this difficult world?  Gay and lesbian couples often adopt children whose (straight) biological parents are unable or unwilling to raise them to properly.  On whose side is the moral shortcoming in this scenario?