"Through the social acceptance of deviant behavior"
The issue here is the fact that many of the people creating the standards, by which you then characterize homosexuals as "deviant", are you, Mr. Vimes, and your homophobic cohorts. Homosexuality, by itself, is in no way an automatically objectional process, like say, murder or incest are.
Therefore the only reason why you have the right to call it "deviant" behavior is because it is people like you whom have claimed to set the standard for what is "proper" behavior and what isn't. And even if it deviant behavior, that doesn't affect you in any way.
Regardless, just because homosexuality is deviant doesn't make it wrong. There are various other characteristics, such as being left-handed, which could be called deviant on a similar basis, yet I don't see you claiming that these behaviors also deteriorate society.
"the deteriation of society due to it"
Please provide a single example of a society deteriorating PRIMARILY as a result of Homosexuality. You have plenty of case studies to choose from- Sparta, Rome, Greece, Egypt, etc. Some of these civilizations have "deteriated", yes, but unless you can prove that this was a result of homosexuality, or that homosexuality was one of the primary factors for such a collapse, you don't have a case.
I'll be waiting Mr. Vimes.