You do realize majorities of both Catholics and Protestants are in favor of gay marriage legalization.
So? That doesn't change what the Scripture says, and the Scripture clearly says that homosexuality is an abomination (Leviticus 18:22, Leviticus 20:13, Romans 1:27, 1 Corinthians 6:9-10, 1 Timothy 1:10). God destroyed entire cities for fornication and homosexuality (Jude 1:7). If you are a Christian, you are supposed to base your morality on what the Bible teaches, not what people around you say. Only God has any moral authority. Love not the world (1 John 2:15).