At present time, all accounts of the physical world are wildly incomplete. The biggest issue, of course, is how the universe came to be. Neither religion nor science can explain how, for example, a higher power could be self-caused or where all of this physical matter came from (specifically, what created God or what happened prior to 10^-43 seconds after the Big Bang).
Yes, most religions claim something like God has always existed or was the cause of him/her self, but it’s quite obvious that these explanations fall well short of complete understanding – for there exists no account of how anything, let alone God, could be the cause of itself (or have always existed).
Similarly, modern day scientific understanding stops at “approximately” 10^-43 seconds after the Big Bang, and prominently lacks a unified theory of the physical universe (we use two very different models – Einstein’s theories of relativity and quantum theory – to govern large and small bodies).
New discoveries suggest it may even turn out that time does not actually exist – which is not nearly as implausible as it may seem at first glance (for we already know that time is not a constant, a nice explanation of this is here – choose the 4th video link).
Imagine a worm, living in the bloodstream, able to distinguish by sight the particles of blood, lymph, etc., and able to think about how each particle is related. This little worm would live in the blood [a part of the body], in the same way as we live in a part of the universe. The worm would consider each particle of blood, not as a part, but as a whole. He would be unable to grasp the larger truth, namely the role the blood plays as a part of the body, and that the blood (his entire world) is only a part of something larger [the body], which in turn is part of something larger still [the universe].
It is impossible for the worm to get on to the larger, ultimate, reality of the universe from the evidence of his world (the blood).
While it may be possible for mankind to expand its understanding beyond that of the worm’s at some point in the future, modern day knowledge of some ultimate reality is on par with the worm. This is evidenced by our inability to answer the most fundamental of all questions – how we came to be – and those referenced above.
The tired athiest/theist/agnostic debate – three worms in blood, confusing hubris for enlightenment.