This is total, stupid nonsense.
First, there is the moral issue. Killing babies is wrong, and undermines everything else. Gay marriage is wrong, and undermines everythig else.
Second, there is the freedom issue. Unless people have religious and moral values, a truly free society cannot exist, because they are incapable of governing themselves. If they cannot impose self discipline, then you need the state police to do it for them.
Third, there is the issue of winning elections. You cannot win elections unless you build a conservative coalition, and that means appealing to the social conservatives, notably Evangelicals. If they stay home, you have lost the election.
That guy who just broke into your house isn’t just stealing your TV. He’s also killing your baby.
And indoctrinating your children into the “gay” life.
Good post!