Wow...for a site made up of agnostics and atheists seems a lot of people don't know the proper definitions of each. Or the fact that the two are not mutually exclusive. Or the proper definitions of deism and theism for that matter. Let's see if I can help with basic definitions.
Agnostic: Lacking knowledge. (In the case of this site the lack of knowledge about the existence of God.)
Atheism: The lack of belief in god(s).
Deism: The belief that some sort of supreme being or God exists. This belief does not imply belief in any specific god(s). Only that something that could be classified as god(s) exists.
Theism: The belief that a specfic god(s) exist and have guidlines for which to follow. This is where the religious would fall under. Those who follow those guidelines tend to form into various religious sects, each with their own version of God.
With all that out of the way please note that agnosticism is compatible with the other three as agnosticism pertains to knowledge and the other three pertain to belief.