Conservatives cannot govern well for the same reason that vegetarians cannot prepare a world-class boeuf bourguignon: If you believe that what you are called upon to do is wrong, you are not likely to do it very well.
If once in America the question of religious toleration was raised in defense of nonbelievers who dissented from religious orthodoxy, today it is raised by believers who feel excluded from a predominantly secular public world.
Iraq failed for the same reasons that all conservative public policy efforts fail. Refusing to acknowledge the importance of government while relying on it to achieve your objectives causes the same kind of chaos in foreign policy that it does in matters closer to home.