Thiests/Athiests, what are your opinions on seperating church from the states?

My personal beliefs is that government should not be driven by petty notions such as being nice, fairness, moral causes, but only for the good of the country in the long run, in other words real politick, hey if its not our problem then why should we get involved? Yet I'm wondering what are the opinions on politics of those whose lives are dictated by religious dogma and those whose lives are dictated to athiesm?