Ed Feser does a much better job than I can do arguing this position in his essay, The Metaphysics of Conservatism. It is well worth the read. Realist conservatives leave room for faith, the others do not. To quote Mr Feser:
So let me end by citing another, and more practical, reason someone with truly conservative instincts ought to favor the Realist brand of conservatism over its rivals -- namely, that it isn't clear that the other versions are really versions of conservatism at all, any more than nominalism or conceptualism are versions of realism.You see, metaphysics matter. Metaphysics determine both our ontology and epistemology.(Our understanding or reality and the nature of knowledge). The Ancient Greek or Roman may have disagreed with the Catholic or Lutheran about the nature of the the true God/Gods, but he would have agreed that there was some form of higher Deity than himself. More importantly, however imperfectly they did it, men orientated their lives to the imperatives of the Deity. The rules came from God, not from a rational agent's opinion of the facts. The locus of morality was external to man. The great cultural divide between the Modern World and the World that preceded it, lay in this metaphysical shift. In the Modern World, Man was the source of morals.
Can an Atheist therefore be a Conservative, if he does not share their metaphysics? I would argue not, for the same reasons Ed Feser does. Can a man be a conservative and disdain Christianity? Yes, but he cannot be a Western Conservative. He can be a Hindu, Buddhist, Confucian etc, type of conservative or he can be a Liberal.
Denis Mangan did not publish my last reply to his post. I really don't care as it is his blog and he has the right to do on it as he pleases. However the generally accepted form is to publish comments unless they are offensive, which my comments were not. I would invite the reader to to visit the discussion and make his own mind up.