My theory is that the Bible is an aggregate collection of stories and most of the events described in it never happened (or at least not as described).
This disproves only the specific God of that book. Similar theories could be applied to other gods if I knew as much about them.
The supporting evidence is not absolute proof, but it's more convincing than anything offered by the opposing theory.
- Many of the stories in the Bible (eg, the Flood) can be traced to older stories belonging to other cultures/religions. The details of the stories are very different.
- Discoveries in genetics, geology, astronomy, chemistry, and other sciences show that life/the Earth/the universe is billions of years old, not a few thousand. For example: the first measurement of cosmic background radiation fit PERFECTLY with the theoretical values calculated from the big bang theory.
- Meanwhile, science has eliminated the need to believe in many other gods. The Nile floods each year because snow melts in the mountains, not because Ra decides to feed his people.
- Christians' interpretation of the Bible (and before that, Jews' interpretation of the Torah) has changed over time, so that the God most Christians today believe in bears little resemblance to the one in the book.
Of course you can believe that the stories were 'corrected' by divine inspiration, that all of science is mistaken, that Ra makes it snow, and that your own personal interpretation is the correct one.
I can't prove a negative. I can only look at the evidence and conclude that one theory fits the data better than the other.
As for creation -
First of all, I don't need a counter-theory in order to reject yours.
Humans evolved from a proto-primate ancestor. So did gorillas, chimps, etc. Going back further, the proto-primate evolved from a proto-mammal, which evolved from a proto-animal. Cells began as pockets of lipids condensing around trapped RNA. Where exactly these constructions can be called "life" depends on your definition.
The Earth formed when gravity slowly accumulated a clump of the denser atoms left over after the sun formed. Lighter elements came from nuclear fusion; all the elements heavier than iron came from supernova explosions.
Atoms formed when the early universe expanded enough to cool enough for electrokinetic interactions to trap electrons in orbitals around protons.
I don't claim to know why the big bang happened. Do you claim to know why God exists?