If you want to stave off a “majority-minority” America, and especially if you want to do this because you think it threatens your culture’s values, then you are trying to conserve central elements of your society. You are, in the most literal sense of the phrase, being socially conservative… Evangelicals, by definition, want to convert people; this second sort of so-con is afraid his community will be converted into something else. Those impulses certainly can go hand in hand, but they don’t have to.
From: Two Kinds of Social Conservatism – Hit & Run : Reason.com