I suppose it depends on what flavor of conservatism you espouse. Ayn Rand, still the darling of many on the right, was a staunch atheist who had nothing but sneering contempt for any kind of religion or mysticism . . . as well as for any sort of thinking that involved any degree of subtlety.
(Sorry, couldn't resist.)
Also, the moral theories of Hume, Smith and Darwin - who all-but-openly rejected belief in a Christian God - have a built-in tendency to favor current social norms: moral sentiments bind us to the opinions of our peers.