How about a definition first -
The Definition of a God
There is often disagreement as to how a god should be described.
I would define a god as a supernatural, conscious, independent being, entity or force capable of interacting with the natural world.
I do not use the word supreme because then there could only be one god. I do not use the words invisible, undetectable, all-powerful, all-knowing, or all-loving since gods need not have these attributes. I do not use the word spirit since it cannot be defined in real terms.
I use the word supernatural because a god must be something different from nature or else it would be bounded by the laws of nature. In that case, it would be too restricted to act as a god.
I use the word conscious because, without a consciousness (implying awareness and volition), the notion of a god is useless. If a god is believed to be an unconscious force, like gravity or electricity, then why view or treat it any differently than these other forces?
I use the word independent to allow freedom of action. A god would not only be free from the laws of nature, but also free from being controlled by other gods. The devil would be considered a god, since he is believed to work his mischief without interference. Angels would not be considered gods, since they are believed to be subservient to an independent god at all times. Greater gods may rule over lesser gods, but lesser gods must have some independence.
I use the phrase being, entity or force to try and cover a range of possibilities. If a god is something other than this, it is outside the realm of human experience.
And finally, I use the phrase capable of interacting with the natural world because a god must have this option (e.g. creation, miracles, answering prayers, delivering souls to heaven, etc.) or it is useless. What good is a god that can only observe, not intervene?
So the question remains: Is there any evidence or reason to believe a god exists? Atheists have concluded the answer is: No.
http://www.atheistalliance.org/library/AB-Defining_God.html