Zero: The number of shits I give about what church any presidential candidate attends or does not attend.
Obviously, I am interested in their religious views, if and when those religious views intersect with their policy positions, but, beyond that, who cares.
It really doesn't tell us anything that Michele Bachmann is/was a Lutheran, even a Wisconsin Synod Lutheran.
I was raised a Lutheran, a Missouri Synod Lutheran, which is only slightly less conservative than the Wisconsin Synod, and, even though the god-belief didn't really stick, I still believe a lot of the stuff I learned there, like "Treat people the way you want to be treated," a message that doesn't seem to mean much to Rep. Bachmann.
I'm not even the only contributor here who was raised Lutheran and is still very culturally Lutheran in a lot of ways. See also: Eastsidekate and PortlyDyke.
What matters isn't what Lutheran church Bachmann does or doesn't attend, in determining her beliefs. People believe what they want to believe, irrespective of what their church doctrine is. Bachmann's behavior and policy positions inform us what her beliefs are.