No, you're right in they could have obstained to i guess prove a pt? Not the same as GOP voters in Cali not voting, b/c literally they won't make a dent of difference.
It's not that complicated though, if you're religious in the US you are likely voting right. Unless you're Muslim, shit even a significant portion of Latino voters vote right for that exact reason.
And there's really no reason to explain this other than the Midwest/South is largely conservative and rural, and that's where religions still has strong holds.