Why not deism?

[Inqwizitor]

Full knowledge is an irrational concept, and an irrational requirement.  

It has to be understood that when we say naturalism provides a complete accounting of x y and z, we're making that statement to the best of our knowledge and/or ability.  Any comment that can be reduced to "but what about what you may not know?" is utterly worthless in the absence of some example to consider.

It's particularly worthless if god is supposed to be the example.  As if, in the "unknown" box....a person can know that it contains a "god".  Begging the question, in the process, of whether gods are in the unknown instead of known box in the first place.  

In the end, the idea that we don't know everything is a deepity, and doesn't advance an argument for god, or even the possibility of a god.  No more so than it would advance an argument for santa or the possibility of santa's existence.

It's not inserting a god, as in, something in some category of being, where there is gaps in our natural knowledge; but stating that natural knowledge itself requires some further explanation or reason for being. There is an old argument, that what knows, and what is known, cannot be the same thing. No matter how much we investigate nature, it is still metaphysically contingent. There are some axiomatic assumptions we must make about reality if we are to make sense of anything, and it's on that same plane that naturalism, as the particular instantiation of observable or measurable phenomena in space and time, is inherently incomplete. It's an existential limitation. @Grandizer suggests that all logically possible worlds could be that explanation; but I think that goes beyond naturalism.