Defining "God"

Defining "God" is a challenging prospect -- nearly as difficult as defining "belief". Really, "God" is a blanket nominal that has come to represent many things. To the ancient Greeks, the Gods were just one of many supernatural beings, which often took forms quite similar to humans, though with extra powers. Today, in Western Society, there is a rising trend of being "spiritual" rather than "religious".
Though I can't be for certain, what I think these people are trying to say is, "I believe in a higher, supreme power, but not as it is described by any institutional religions." There are also those who claim that God is "Love" or any number of human emotions which represent "God". Are these things truly Gods? Is there a difference between Zeus, Yahweh, Jesus, Allah, Brahman, a "higher power", or a "natural energy"? Defining myself as an atheist or antithiest, I am defining myself as the opposite of a theist, but to understand what a theist is, one must understand what a God is.
The difference, as I see it, between a character like the Christian God and a label such as "love" or "natural energies", is that the former has his/it's own will, whereas the latter does not. A God, in the institutionalized sense of the word, has desire. There is something you must do for God. There are rules you must obey or even missions you must accomplish. A "natural energy" makes no such request of it's followers. It has no will or desire, it simply is. It is the woven fabric of the universe that is beyond our power to comprehend, or at least, that is what I think these "spiritual" people are describing to me.
So really, God for anybody is the highest possible power. Institutional Gods are generally modeled after human beings, complete with all of our flaws (wrath, vengeance, and in the case of Zeus even lust). They also tend to be warped by those who evangelize in their names. More "spiritual" Gods, on the other hand, are in my opinion simply an attempt to describe powers which we don't understand. These descriptions do not even necessarily make any assumptions about supernatural powers.
God is everything, the universe, all of it. And in this case, plain old secularists have taken the institutional word and warped to simply describe one's perception of the universe, be it optimistic or pessimistic.
These "Gods", I can deal with. But "anti-institutional-traditional-dieties" is a rather long nomer, and so I think I'll just stick with "atheist".