Religious Definition of the American South

Please forgive the lack of posting lately; I've been moving from College Station, TX, to Charlottesville, VA.  Having previously lived in Maryland and the Federal City, and having married a gal from Mississippi, I've thought a bit about what defines the American South.  The conventional definition is that "The South" consists of those states which declared their succession from the Union during the Civil War.  But such a definition pegs current cultural divisions to events which happened a century and a half ago.  I certainly believe history matters, but it still seems a curious way to cast the definition.

I was struck, however, by this map of religious observance in the US:

The concentration of Baptists in the South is striking, a point made even more striking by its obverse: almost nowhere outside the South do Baptists form a plurality.

Religious identity adds some interesting developments to the definition of the South.  Almost anyone will tell you that peninsular Florida is not culturally South; the religious map bears that out.  Likewise, although West Virginia was created as an anti-Confederate state, many West Virginians today seem to have forgotten that, a fact likewise paralleled on the religious map.  On the other hand, many Southerners (or those from the Deep South, ie Mississippi to South Carolina) contend that places like Texas and Missouri are not really Southern.  I'll not enter into that debate, but the map suggests they at least  belong in the Greater South, as does southern Illinois, which is certainly culturally distinct from Chicago and the north end of the state.

Map courtesy of American Ethnic Geography.