This is like asking your average American if our own laws should be guided first and foremost by the Bible. I imagine you could get a good half of Americans to agree on that. But can you get even 10% of them to agree on exactly what that means? In anything but the most broad and nebulous terms? I doubt it.
It's not news that fundamentalist (and many somewhat less fundamentalist) Christians think that the US should be guided by the rules laid out in the Bible. It does, however, put the current hysteria over Sharia law in a slightly worse light. It's not that our law system would be guided by religious principles rather than the constitution, but that it would be guided by the WRONG religious principles. It would be nice if these people (looking at you, Rep. Peter King) would just up and say "we don't like Muslims". At least then we're arguing over the right things.