There was a clear linear progression for both candidates in 2012, with Mr. Obama's support rising as church attendance falls and the opposite true for Mr. Romney.
The church attendance differences are most stark when you look at Catholics.
Yes, Mr. Obama won the overall Catholic vote in 2012, but Mr. Romney beat the president handily among Catholics who attended church at least weekly - 57% to 42%. In fact, those figures matched exactly the margins Mr. Romney had over Mr. Obama with Protestant Christians.
But among more casual Catholics, those who attend church less than once a week, Mr. Obama defeated Mr. Romney with similar ease - 56% to 42%. (There are similar differences among protestant voters, though Mr. Romney won both regular church attendees and less-frequent churchgoers.)
The message in these numbers? There will not only be more people in the pews around this weekend in your house of worship, there will probably be a different body politic.