To me - a homosexual is a person who engages in sexual acts with members of the same sex.
It doesn't matter what it means
to you. It matters what medical science says it is. This is where a lot of the problem comes in: too many people who believe they're "authorities" because they "read the bible" or "believe in Jesus." There must be agreement as to what terms mean, and as to what social standards are. And that's not up to
you.
Marriage - as defined by God - is only between men and women.
God doesn't define marriage. Ever. The biblical writers define marriage. There's a difference. One is immutable. One isn't. We have to be very careful about what we term "immutable" or "God's will," when dealing with a diverse society and when we cannot know for sure just what "God's will" is. The biblical writers wrote from their own knowledge base and cultural perspective. Neither is shared by us. Therefore, probably not the best thing to declare that what
you "believe" is immutable. Immutability in that context invariably ends up excluding some. That's not what God had in mind.
Paul in
Romans 1 clearly condemns homosexual acts for both men and women.
Paul clearly condemns some
same-sex acts. We don't know specifically what acts they are, or in what context. Nor is it clear that those acts arise out of a homosexual orientation. Not all same-sex acts are
homosexual acts. Are the acts loving? Committed? Consensual? Equitable? A method of expressing love and commitment to another human being? If so, many would define that as "marriage," and marriage is aces in God's book -- doesn't matter if the acts are heterosexual in nature or homosexual in nature.
BTW: I'd be careful about slinging too many rocks at the homosexual marriage thing, since
your tradition historically practiced polygamy -- even though it was illegal in this country. And before you defend that practice by saying "times change and God issues new revelations from time to time," consider that God has issued a new revelation to many Christian authorities with regard to same-sex marriage, as well. And
that's legal in this country.