That's not because Republicans are pro-life and pro-traditional marriage; even if Republicans ignored the issues -- as, indeed, Mitt Romney tried to do -- secularists would still link a larger state with a pro-abortion, pro-same sex marriage position. That's because the same position that rejects the sanctity of unborn life tends to reject the sanctity of private property; both are based on the John Locke-ian premise that man is special in the universe, and that the product of his labor is an extension of his special place in the universe. Ignore man's Godly origins and his property becomes a dispensable commodity rather than a fulfillment of a divine mission.
More than that, the religious society rests on two fundamental principles: personal responsibility and belief in responsibility to future generations. Secularism rejects both principles. Personal responsibility becomes societal responsibility in the secular view; we are all shaped by our genetics and our environment, both of which are out of our control. How, then, can we be held responsible for our actions? As for responsibility to future generations, the prophet of modern day leftist economics, John Maynard Keynes, summed it up best: "In the long run, we are all dead." Tap out the public treasury now, and grab your redistributionist cash for there is no kingdom of heaven -- and you won't be around to reap the consequences of your decisions.
Perhaps libertarianism is a solution. But historically, it hasn't been. Every godless society has turned radically to the left. There are religious societies that turn to the left, too -- Islamic societies tend toward Marxist economic schemes -- but the traditional Judeo-Christian philosophy has forwarded capitalism.
So, can American society survive its turn to secularism? It can, but only in a different form -- a more European form. The best hope for a return to fundamental American principles is a return to the fundamental American philosophy embodied on our coinage: E Pluribus Unum on one side, In God We Trust on the other.