Republicans have cultivated religious whites by promoting issues which strike a resonant chord with these voters. Many religious whites are genuinely concerned about erosion in morality and values which they tie to their Biblical faith. Republican efforts to oppose such issues as same sex marriage, abortion and embryonic stem cell research have fallen on sympathetic ears.
Nothing works as well in elections as emotions, and religiously based emotions are some of the most powerful of all. Convincing religious voters that a vote for Republicans means a vote for stemming the tide of secular humanism and the eroding moral and family values has been a highly effective technique for the GOP.
Of course, it's now perceived as uncivilized to openly encourage racism, but the code words are prevalent when GOP operatives imply that people of color and "their movements" or "their counter culture" are partly to blame for proliferating "secularism."