Pro-life. It suggests that this person is merciful, and anyone not for life is a baby killer. Sanctity of Marriage. It conjurs up images of what is pure, Godly, just, holy, and right. Anyone trying to change that is disrupting the consecration of Marriage.
We need to choose loaded language, and use it against them. Let's take gay marriage as an example.
Rather than Gay marriage, which makes people feel icky, call it Equal Rights, what's Fair and Equal. Marriage for loving monogomous people. Or, better yet, use the Republican's ideas against them; the boogeyman of big government telling them how to live. Pro-independence, pro-small government, etc.
Maybe I'm not making as much sense as I can. Hrm. Ideas?