Why is God so concerned about what consenting adults do in their own bedrooms? First, because EVERY person bears the image of God. YOU do not belong to YOU. Second, what you do, even in privacy, effects everyone around you.

Do not make yourselves unclean by any of these things, for by all these the nations I am driving out before you have become unclean, and the land became unclean, so that I punished its iniquity, and the land vomited out its inhabitants.
Leviticus 18:24-25

Open sexual perversion defiles the entire nation, not just those who practice it. Homosexuality, incest, bestiality, etc. are NOT victimless crimes. If you love your neighbor, if you love your country, you will not tolerate such things.

#leviticus 18:24-30 and Acts 15