Interestingly, it's not religious against non-religious. It's religious liberals on the political left and religious conservatives on the right. The current issue dividing the two may be different, but the underlying core ideas are the same.
One difference in today's landscape is that Roman Catholics used to be Democrats, by and large. However, now the conservative RCs have been driven from the left (e.g. Gov. Casey in PA) over the abortion issue and now homosexual marriage.
The political left cannot connect with the "heartland" because the source of its core values is completely different from those it will try to chase.
The religious divide existed for a very long time, but it was over religious dogma.....who believed what.
Abortion, prayer in schools, same sex marriage, are unifying religious issues.
Looks like the more radical the Left got, the more united believers became.
Too bad Lefties.