This is fascinating, and somewhat depressing. The Economist found that religion or lack thereof is the number 1 predictor of voting patterns. Atheists overwhelmingly vote Democratic; evangelicals overwhelmingly vote Republican. It is not clear whether the personal character of the candidate is even a factor, even though evangelicals insisted, nay demanded, that personal character be an essential factor during the Clinton administration.
What would it take to make a white evangelical vote for Democrats? All the variables would have to line up, and even then, the chances are only slightly better than half.
The link has a fun, interactive feature. You can choose whatever mix of demographic variables you want and find out the probability that you will vote either for Democrats or Republicans. My score, based on my demographics, was a 57% chance of voting Democratic, a result that probably goes a long way toward explaining why my voter registration says “unaffiliated.”