"Jesus would rather kill, not marry, gay people" - Franklin Graham

[RoadRunner79]

I don't think that you rationalize to morality.   You may have to rationalize from moral principles for something which is a little different.  But I don't think that you get to those principles through logic.  How do you rationalize that it is wrong to kill others.   At best you may take a pragmatic approach, but a pragmatic approach, but being pragmatical doesn't necessarily make it moral or immoral.  Otherwise your not saying that it is right or wrong, but efficient.  As well, the question doesn't even make sense in a subjective view of morality.

Killing others causes objective harm, the pain and suffering of both the person that it killed and their families and loved ones. Two men or two women having sex does not, unless you count a feeling that something is icky as objective harm.

That is a mis-characterization and I think you know it (feeling that something is "icky").   And I've been down this road before the presence or absence of objective harm, doesn't make something moral or immoral. It doesn't account for objective morality. Or say why it is wrong (only that it causes harm)    If you would like to make a thread, we can discuss why you think it does and I think that it does not.