The subject of Deism came up in another thread, but I think the Deist belief system is worthy of a fuller discussion. It is a belief in a God without the hocus pocus of the "revealed" religions like Christianity. I'll re-post what I said in the Agnostic Forum thread:
Here's a Deist website with a FAQ: http://www.deism.com/deism_defined.htm
I'm not a Deist, but I'd answer your questions based on my understanding of Deism as follows:
It would be more correct to say that they're not sure what God's "business" is.
They believe God exists because they reason it is likely there was a Creator. They were big on the idea of the Watchmaker - the universe is intricate, intricate things are designed, etc. etc. More recent scientific findings that the universe's forces are within narrow limits that allow life would be consistent with this viewpoint (though there are alternate explanations like "many universes" and "MetaLaws".
EDIT: Here's a rather beautiful quote from Tom Paine that is on the cited website:
"I consider myself in the hands of my Creator, and that he will dispose of me after this life consistently with His justice and goodness. I leave all these matters to Him, as my Creator and friend, and I hold it to be presumption in man to make an article of faith as to what the Creator will do with us hereafter."
So, any takers?