Take a look at this data from Pew Research.
Religiously unaffiliated voters and Jewish voters were firmly in Obama’s corner in 2012 (70% and 69%, respectively). Compared with 2008, support for Obama ticked downward among both Jews and religiously unaffiliated voters in the exit polls, though these declines appear not to be statistically significant. Both of these groups have long been strongly supportive of Democratic candidates in presidential elections. Black Protestants also voted overwhelmingly for Obama (95%).
[...]At the other end of the political spectrum, nearly eight-in-ten white evangelical Protestants voted for Romney (79%), compared with 20% who backed Obama. Romney received as much support from evangelical voters as George W. Bush did in 2004 (79%) and more support from evangelicals than McCain did in 2008 (73%). Mormon voters were also firmly in Romney’s corner; nearly eight-in-ten Mormons (78%) voted for Romney, while 21% voted for Obama. Romney received about the same amount of support from Mormons that Bush received in 2004. (Exit poll data on Mormons was unavailable for 2000 and 2008.)
Compared with religiously unaffiliated and Jewish voters on the left and white evangelicals and Mormons on the right, Catholics and white mainline Protestants were more evenly divided. Among white mainline Protestants in the exit poll, 54% voted for Romney, while 44% supported Obama. This is virtually identical to the 2008 election, when 55% of white mainline Protestants voted for McCain and 44% backed Obama.
White Catholics, by contrast, swung strongly in the Republican direction relative to 2008. Nearly six-in-ten white Catholics (59%) voted for Romney, up from 52% who voted for McCain in 2008. Three-quarters of Hispanic Catholics voted for Obama, and Catholics as a whole were evenly divided in 2012 (50% voted for Obama, while 48% backed Romney).
I am actually one of those rare non-white evangelical Protestants who is strongly pro-life and pro-marriage. I believe that the Bible is the Word of God, and that it prescribes true moral values and moral obligations. There are not too many of us in America, according to these exit polls. I am very proud of my fellow evangelical Christians. We take the Bible seriously as a moral guide, and it affects everything in our lives – including how we vote.