Wrong, unfortunately. There's a correlation between frequency of attendance and conservatism. While not the whole voting chart, here's the relevant subset:
65% McCain, xx% Obama - Weekly church-attending Protestants7
55% McCain, 43% Obama - Weekly mass-attending Catholics 6,9
54% McCain, 44% Obama - Weekly church-goers1,4,7,12
54% McCain, 45% Obama - Protestants6,8
52% McCain, 47% Obama - White "regular-mass-attending" Catholics12
46% McCain, 52% Obama - Non-Evangelical Protestants 12
xx% McCain, 53% Obama - Monthly church-goers 4**
45% McCain, 54% Obama - Catholics1,4,6,8,9,10,11,12
xx% McCain, 59% Obama - Semi-annual church-goers4**
38% McCain, 61% Obama - Occasional churchgoers1
37% McCain, 61% Obama - Non-weekly-mass-attending Catholics6,12
xx% McCain, 68% Obama - Don't attend church4 **
23% McCain, 75% Obama - Unaffliliated with any religion11
I am assuming this figure includes Blacks and Hispanics, bringing the 75% figure for White protestants as a sub group down to 65% for all Protestants. I'm figuring the Hispanic figure doesn't impact the Protestant % as much as Blacks because more of them are Roman Catholic.