Ok. So I've got a minute to spare. Why not argue definitions with Jan and shoot the breeze eh?
How could God possibly exist to an atheist (a person without God)?
You're mixing the subjective with the objective, perhaps.
It seems fairly obvious that for a person who believes in God, God exists, and for one who does not, God does not exist. That's subjectivity. More often, though, we're interested in whether God
objectively exists, independent of what any given individual believes about the question.
How can existence be the foundation of the terms theism and atheism?
I can't speak for your particular brand of theism. But as I understand the term, an atheist lacks a belief in the existence of God. That is, the atheist sees nothing that leads him to assent to the claim that God exists. This is not the same as holding that God does not exist, of course. Many atheists leave the door slightly ajar. It is always conceivable that God might exist after all. New evidence might come to light. Who knows? Atheism is a belief claim, not a knowledge claim.
I don't particularly see why your concentration on the etymology of the words "theist" and "atheist" is important. They are, after all, just labels for particular belief systems, just like "cup" is a label for a particular kind of drinking vessel.
There is no definition that translates as being with God, only, being without God, you don't need to believe me, it is in the labels we use.
And this is important because ...?
There are lots of examples of the same kind. Consider, for example "periodic" and "aperiodic". One word describes something that repeats regularly; the other describes something that does not. It's just a Greek derivation of some English words. You shouldn't read into it more than is there. It's not like you'd argue that there is no word that translates as being
with period, only a word for being
without period, like that was some kind of deep distinction.
If what I say is true (and there is no reason for it not to be), then we can become atheist whenever we choose to be, because atheist simply means (without God).
And by the same argument we become theists whenever we choose to be, because theist means somebody who believes in God. You're assuming that all people choose their beliefs by some mechanism, I suppose.
The question is: What does it mean to be without God.
If there is only God (Theos), to be without God is like wearing breathing equipment all the time, refusing not to breath air.
I'm not sure I'm parsing your example correctly. But the gist seems to be that because you believe that God exists, you think atheists must be wandering the world oblivious to God's wondrous presence in all things. Any atheist would argue, to the contrary, that you're wandering the world harbouring a delusion that you're in magical touch with a supernatural force that probably isn't real.
If I am without God, then my life is one where I don't give any real consideration to it.
I don't need to consider God, to have a life that I enjoy.
If I'm basically a decent person, with no bad intentions to my fellow man, I could quite easily be without God in my life.
You should not assume that all atheists are the same. The only thing that two atheists can be guaranteed to have in common is that they share their lack of belief in God. Some atheists spend quite a bit of time contemplating the question of God; others don't give it much consideration.
I'd say that the more important question to most atheists is: what implications does it have for human beings to believe in a god or gods or God, or whatever you like, vs not believing in any of those? What
follows from what people believe or do not believe,
independent of the objective truth of the matter? For example, is religion a net force for good, or ill?
A-theist literally means without God. 'Existence' or lack of, can be seen as a reason why one is without God. 'Existence' (lack) has become synonymous with atheism, but it isn't the true definition of atheism.
The best definition of atheism would follow from what atheists say about themselves, would it not? You insist, after all, that the best definition of theism is the one you yourself hold to.
It doesn't matter, existence is a reason for being without God.
In that light,God wearing crappy shoes could also be a reason.
I hope you can see that those are different. In case (1), one is without God because there is no God and so it is impossible for anybody to be with God. In case (2), one is without God because one has rejected a presumably-extant God.
Of course, in case (1) it could be that one
believes that the in-fact-extant God does not exist, and so one is only
subjectively without God, which would put (1) closer to (2). It could also be that one only
believes that an actually-non-existence God has crappy shoes, and so one would be rightly rejecting God but for the wrong reasons. Or something.
The position the atheist holds is one of being without God. The reason, they claim, is a lack a belief in Gods existence.
Or the reason, they claim, is that God (probably) does not exist. A subtle but important difference.