I don't think Christians are doing that. If it seems as though Christians are condemning homosexuality more than other sexual sins, it's only because homosexuality is the only sexual sin that we are constantly told we must celebrate. The day when there are "adulterers' pride parades" or "pornographers' pride parades" marching down the street, Christians will talk as much about adultery and pornography as they do homosexuality.
It is not uncommon to see churches celebrating sin. A church may celebrate wealth as a sign of God’s favor. A church may preach disobedience against government leaders with whom they disagree.
My church back home justified slavery and Jim Crow along with supporting tobacco use. Churches have frequently allowed culture to drive the message.
My last two churches had to change Scripture to remove language that went against church teachings.