Fr. Dwight Longenecker blogs on the sin of Sodom. Read both pages of the article.
I don’t agree with him that the sin of Sodom “is not simply homosexual actions” but included violence. Although the men in the story were also committing rape, what distinguished this city from others was not rape (which unfortunately occurs in all large cities) but the complete acceptance of homosexuality by that society (a direction our society is moving in).
However, he does make some good points:
“If a same sex couple engage in sexual intercourse, and both parties are consenting they may not be doing violence to each other in the blatant way that the men of Sodom intended, but they are still doing violence to one another and to the natural order and to the sacrament of marriage.”
“Furthermore, we sometimes forget that it is possible for heterosexuals to commit sodomy.”
“What we are talking about therefore — whether it is between two men or a man and a woman is un-natural sex — a sexual act that is not procreative and therefore not fully loving as God intended — a sexual act that is for pleasure only. Such behavior, by anyone is called a sinful action. This is an objective judgement based on natural law. Male and female genitalia are designed for a purpose and to use them otherwise is un-natural and therefore sinful.”
The question of unnatural sexual acts between man and woman, between husband and wife: Unnatural sexual acts as marital foreplay. Although many persons online (most of them anonymous) adamantly assert that married couples may use unnatural sexual acts for the purpose of foreplay, or, they claim, for any purpose at all for the wife, the Church teaches no such thing.
The Magisterium teaches that each and every sexual act must be that type of sexual act that is inherently procreative (natural intercourse). Unnatural sexual acts are non-procreative and also not truly unitive, and so all such acts are intrinsically evil, even between a man and a woman, even within marriage, regardless of the purpose (e.g. foreplay) and regardless of the circumstances (e.g. that the wife did not reach climax by the natural act). Neither does the absence of climax in an unnatural act make the act procreative or unitive or at all moral.