"Democracy demands that the religiously motivated translate their concerns into universal, rather than religion-specific, values. It requires that their proposals be subject to argument, and amenable to reason. I may be opposed to abortion for religious reasons, but if I seek to pass a law banning the practice, I cannot simply point to the teachings of my church or evoke God’s will. I have to explain why abortion violates some principle that is accessible to people of all faiths, including those with no faith at all. Now this is going to be difficult for some who believe in the inerrancy of the Bible, as many evangelicals do. But in a pluralistic democracy, we have no choice. Politics depends on our ability to persuade each other of common aims based on a common reality. It involves the compromise, the art of what’s possible. At some fundamental level, religion does not allow for compromise. It’s the art of the impossible. If God has spoken, then followers are expected to live up to God’s edicts, regardless of the consequences. To base one’s life on such uncompromising commitments may be sublime, but to base our policy making on such commitments would be a dangerous thing."
Panderbear expressed much the same sentiment in Principle vs Policy, though not nearly as well as President Obama.