Most Theists are 99% Atheists
What I mean by that is, your typical theist (lets say for specificity's sake we mean Christian), will deny the existence of Egyptian gods like Ra and Horus and Anubis, or Zeus and Poseidon, or Mars and Jupiter, or the Mesopotamian gods or the deities in Native American cultures or any god but their own. How is your god any more or less real than Zeus? Don't tell me it's because of the Bible. What makes the Bible so special? There's literature that talks about Zeus' desires too, and those of Aphrodite and Hera and all the gods-it's Homer's Illiad and Odyssey.
Even if you argue that those poems weren't divine or divinely inspired like the Bible, it doesn't change the fact that the Ancient Greeks knew what the gods wanted, just like you know what your god wants. But how are two primordial beings creating the earth and time, have children that fight and then have children of their own and one of these first children eats 3 of the grandchildren any more or less realistic than a single primordial being creating the earth and time and the sun and the stars and everything and then taking a break after 6 days?
At present there an estimated 30,000+ Gods/Deities worshipped around the world and every worshipper will loudly proclaim that theirs is/are the 'One True God/s.'
In human history there have been an estimated 300 MILLION different Gods/Goddesses, etc, worshipped yet every one of them has eventually fallen by the wayside at some time or another only to be replaced by a 'better' version.
Every Deity created in the mind of man carries the traits, both good and bad, of Man because that is how humans create them in the first place, imagination is very powerful thing, it can either bring joy, knowledge, contentment, etc, OR, as in the case of religion, repression, suppression, divisiveness, hatred and everything wrong in society.
Richard Dawkins said "We are all atheists about most of the gods that societies have ever believed in. Some of us just go one god further". Every religion denies every other religion, and will vow theirs is the only true god. Thank the FSM that they're all wrong. Every one.