So Yankee, you're basically saying that Baptists are to the GOP now what Calvinists and Congregationalists were a century ago?
You must consider that the Civil War also split the churches as well. Presbyterians and Baptists were Democratic in the South, but I would hazard a guess they weren't quite so monolithic in the North. I really prefer to avoid getting into the weeds of religious groups and their differences, but aside from wealth and geography religion was more factor the broke down along party lines where there party lines to be drawn (since the South did not have parties it had factions within the Democratic Party at that time).
Wouldn't presbyterians be solid GOP in the North a century ago? They are one of the wealthiest denominations in terms of per capita income.