Who said anything about selling? My post only makes reference to making something which is of high value into something cheap, worthless and devalued i.e. "Why Bother with normalcy when peversion is the norm."
The argument by homosexuals is that their "marriage" doesn't have any adverse effect on the heterosexual marriage of one man and one woman. Also notice how quickly this argument has become the rallying cry for homosexuals via their "Vast Pink Conspiracy."
But when perversion makes a mockery of something it does not make that perversion moral.
Homosexual marriage is not the issue. Total acceptance of homosexuality is the issue.
You did: "mobile homes [...] decrease the value of the neighbors' houses." That statement is true only for the *sale* value; the intrinsic value of a home to its current occupant is lowered not a whit by a neighboring mobile home. In the same way, the value of a Christian marriage is lowered not a whit by an un-Christian marriage.