Hello! I am new to the boards and thought perhaps I could try and write some insight, not as to command the discussion, but as to view our enquirers in another direction.
I like where Arvy is going by proposing the following:
To make your question more sensible, you should ask yourself "How many gods does X religion believe in?"
However, even though I am religious, I think that perhaps we ought to try to establish / disestablish whether a god or gods exist outside of religion, or at least not use religion in establishing a deity's existence. Now, I know my argument may be biased towards a Christian viewpoint, but this is a point that I cannot escape, seeing that it is what I believe.
For me, perhaps the most effective argument for the existence of God is in the Cosmological Argument (taken from Aquinas). Although its origins is Christian, we can easily strip away the elements of Christianity into a completely causal argument. As I understand, it is as follows:
First, we must accept the Principle of Sufficient Reason: "For every fact there is a reason why it is so or why it is not so." Put into terms of causality, this means that every effect must have had a cause, either in itself or in another.
Every one action (a) must have a cause for that action. And prior to that action (a), there must have been another action (a1) resulting in the possibility of that action (a). If we follow a line of causality backwards, we either follow causality to infinity, which is impossible, for all nature must have had a starting point. Thus, it is sensible to think that there must have been some first cause that moved into effect everything that now exists. That first cause would be God.
Now, I am sure many heavily scientifically minded people would gawk at this assertion - as would atheistic peoples - but it is hard for me to comprehend why either people would give reality's origins as random chance; or refuse to explain its origin altogether (by asserting that the causal chain regresses to infinity).
However, if we find this argument unacceptable, we should at least try and find a reasonable argument for the existence of A GOD and what qualities A GOD may have before we delve into the possibility of sub-deities. One can surely appeal to religion and say "well, I believe in God," but as this is a philosophical forum, I think that would be quite an unsatisfying answer for most of us. If there are metaphysical beings, surely our reason can understand them somehow.
I look forward to the rest of this discussion.