Have a look at Amy Sullivan's thoughtful piece from Slate on the Democratic Party's declining appeal to religious voters.
The Pew Research Center's annual poll on religion and politics, released last week, shows that while 85 percent of voters say religion is important to them, only 26 percent of Americans think the Democratic Party is "friendly" to religion. That's down from 40 percent in the summer of 2004 and 42 percent the year before that—in other words, a 16-point plunge over three years. The decline is especially troubling because it cuts across the political and religious spectra, encompassing liberals and conservatives, white and black evangelicals, mainline Protestants, Catholics, and Jews. The Republican Party also experienced a drop in the percentage of Americans who say it is friendly to religion—eight points over the past year. But that decrease occurred mostly among white evangelicals and Catholics and the reasons for it seem obvious: Two years of broken promises by the GOP.
In contrast, the Democrats' crumbling credibility on religion wasn't caused by one thing. And that may be the problem. All at once, the party needs to counter conservative attacks, change the conventional wisdom that Democrats just aren't religious, and expand the party's reach to moderate religious voters. To do that, the party will need a little more faith and a whole lot more work.