God, ministers, and politics
Once upon a time American politicians were not always so eager to have the clergy involved in politics. A number of antebellum state constitutions banned active ministers and priests from holding political office. This ban had its roots in the rejection of state-sponsored religion, particularly in the former colonies where the Anglican Church had been strong. It was reinforced in the late antebellum era, at least in a few places, by the association of the antislavery movement with some northern ministries.
In parts of the North, the antipathy that many mainstream politicians had for evangelicals pushing issues like temperance was quite high in the 1840s and 1850s. Of course, the efforts by some northern evangelicals to increase their political influence in the face of such antipathy was one factor in the creation of the Republican Party.
A ban on active clergymen holding office would be unconstitutional today, and rightly so. More practically, truly enforcing such a ban—and I’m not sure that one was ever put to the test—would require government to figure out just who is or who isn’t an active minister. That might even be harder to figure out than whether or not some bloggers are journalists.
Still, religion is not going to leave the current campaign. The recent California Supreme Court decision on gay marriage has energized many conservative Christians who are part of the Republican’s base. Whether the issue will have the same traction this year as in 2004, I doubt, but on balance it is still likely to help McCain some, if only by getting some of those Republican evangelicals who are suspicious of him to vote anyway.