The LDS church's argument against same-sex marriage.
Here is a press release with official church pronouncements on its stance against same-sex marriage.
It looks like the document, "The Divine Institution of Marriage" contained in this press release may become an official proclamation of the church.
It seems to ably present the major arguments against same-sex marriage, not just from a religious standpoint, but also from a societal and cultural standpoint.
There are some issues in it that I have not read before. And there are some more controversial issues left out.