I always thought it went
P: Sex outside of marriage is a sin.
Q: Marriage is between a man and a woman.
Therefore [P and Q] implies that homosexual activity is wrong but the mere act of being attracted to the same sex is not inherently sinful.
P: Sex outside of marriage is a sin.
Q: Marriage is between a man and a woman.
Therefore [P and Q] implies that homosexual activity is wrong but the mere act of being attracted to the same sex is not inherently sinful.
As for why that should influence our votes for public policy, the reasoning goes that sin always brings trouble, death, and non-well-being to society, therefore influencing public policy away from sinful societal patterns and acts is one important way to love one’s neighbors, since it will result in greater well-being for them.