although the idea makes no sense - actually, in a way, a lot of people already live like that - in that many people will say they believe in god - but they don't pray or go to church, or really believe in some of the stories in the bible, such as noah, moses, loaves and fishes etc, they don't have crosses or religion paraphernalia in their houses, they generally don't do anything religious whatsoever.
i think also those people are the people who do not commit atrocities in its name.
under analysis and scrutiny their 'belief' would fall down, but in day to day life many live with god but with no religon...