Should Republicans give priority to born-agains or moderates? The short answer is the former. Here are the reasons.
Reason number one: Looking at NYT exit polls, we see that 57% of them voted for McCain, and the share voting for the Republican has ranged from 56 to 74 since 1980. A majority of them reliably support our side and thus should be rewarded with the party's loyalty. Democrats reliably get moderate majorities (with the exception of 1984) so we owe the middle nothing.
Reason number two: You might counter that since BAs are the base, they can therefore be taken for granted. The fact is that this group swings about as much as moderates. The range of the swing for born-agains since 1980 is 18 points; it's 22 points for moderates (and the low end of the swing for the latter was caused by the anomaly of Perot). Not only do BAs swing alot, they are notorious for staying home if they are unenthusiastic, and they can decide elections if they get fired up (as in 2004).
Reason number three: Once again, you might respond that, unlike moderates, they are a small group. In 2008, they are 38% of the electorate versus 44% for moderates. Yes, I know that some of the BAs are blacks, but so are some of the moderates. Add to this that BAs are growing. In 2004, white BAs were 23% of the electorate; now they are 26%.
Reason number four: The Republican track record is better when we put up non-moderates. Reagan garnered 59% of the vote in 1984. A weak candidate, Bush II was elected two times. Moderates are losers: Ford, Dole, McCain. Bush I was a one-termer who owes his victory to the non-moderate Reagan.