As a South Dakota atheist, let me say that if Moore's contention were true, there'd be no such billboards, or at least no news reports about them. We also would not see "Christian" in the first sentence of any Senate candidate's bio. (Rhoden waits until paragraph 4 to establish his Baptist cred; Rounds doesn't mention his Catholicism in his current Web bio).
The Coalition of Reason makes a declaration of moral intent that should be culturally helpful for any candidate or citizen of any religious persuasion:
Members of our community and student organizations self identify as atheist, agnostic, humanist, freethinker, secular, skeptic, non-religious, rationalist, empiricist, and more. Like everyone else, we also benefit from a supportive community of friends and family. South Dakota CoR strives to foster a better understanding of our secular values with our neighbors, and to promote and defend those values in our government. No matter how you self identify, we affirm that all have the ability and responsibility to lead ethical lives of personal fulfillment that aspire to the greater good of humanity [emphasis mine; South Dakota Coalition of Reason, "Welcome," downloaded 2013.08.23].I can hear my theist friends and even my own skeptical soul asking, "But where does that responsibility come from? Why bother with the 'greater good of humanity' if there is no God?"
I lost little sleep over that question when I was younger; I lose no sleep over that question now. If I didn't behave ethically, my daughter would be sad and my wife would be mad. If no one behaved ethically, life would suck. That response is selfish, sentimental, and sloppily utilitarian, but it works.
Some Christians I know will still declare the Coalition of Reason's commitment to ethical living empty and flimsy: how can we rely on a secularist's professed principles when they are rooted in nothing more than personal choice?
I do not doubt that atheists may make mistakes and fall away from their principles. But in that fallibility, do atheists differ at all from Christians? My Christian friends choose, with the same faculty of free will exercised by me and my secular friends, to follow the teachings of an ancient tribe that caught heck from Pharaoh and walked around the desert a lot, with amendments by a carpenter and convicted criminal from Nazareth. Prominent in those teachings is the idea that all people are fallible. We all suffer weakness. We all make mistakes. Are Christians not by definition as prone to waver and err in their convictions as everyone else we meet in the street?
I'm not big on joining clubs. I've never gotten the sense that joining a Christian club would help me make wiser, more humane, more effective decisions. I don't think joining an atheist club will bolster my decision-making ability.
But I do hope that the South Dakota Coalition of Reason can build on these new billboards to open lengthy conversations between people of all faiths—in God, in Wakan Tanka, in human dignity—that will help us all understand our common abilities and responsibilities to build a better world for all of our relations.