Slave States and Religion

Here are the fifteen slave states and two territories in which slavery was legally practiced prior to the American Civil War. To each I've added an ostensibly unrelated ranking from a relatively recent Pew Forum poll:

Mississippi (1)
Alabama (2)
Arkansas (3)
Louisiana (4)
Tennessee (5)
South Carolina (6)
Oklahoma (7)
North Carolina (8)
Georgia (9)
Kentucky (10)
Texas (11)
Utah (12)
Virginia (15,18)
Missouri (17)
Florida (20)
Maryland (21)
Delaware (24)

Before I tell you what the ranking means, I'd like to point out a few obvious things. Firstly, all of these former slave states are clustered in the top half of the states, which is statistically vanishingly unlikely on chance alone. Moreover, every single one of the top twelve (12) states in the Pew poll are formerly states or territories in which slaveholding was legally practiced.

Now, here I the kicker: The Pew Forum poll had nothing to do with slavery or race or even civil rights. It was merely a measure of religious faith, and not even some particular religious faith historically tied to denominational support for the institution of Negro slavery, but really just ANY faith at all.

Now, here is the poll page itself:
http://pewforum.org/docs/?DocID=504&loc=interstitialskip

I know as well as the next stats geek that correlation is not (necessarily) causation, but these massive overlaps cry out for some common factor. What is it about faith which facilitates slavery, or vice-versa, or what might be the hidden variable here? Is it that religious faith allows people to override their own sense of morality, which might well balk at seeing a fellow human in bondage? Is it that some Christian sacred texts expressly condone slavery? Or is it something else entirely?