Is agnosticism a reasonable belief?

There is an argument against God that I've lately been seeing repeatedly.  It goes something like this: "just because you can't prove there's a tiny teapot orbiting Venus, doesn't mean it's not there" or "just because you can't prove that the East Bunny is real doesn't mean that he isn't."  Implying that both these situations are so unlikely that we might as well assume that they are false and the statements are therefore logical fallacies.

A God or gods, unfortunately, are not the equivalent of the Easter Bunny or a tiny teapot orbiting Venus or a dragon flying around Saturn's rings or whatever other absurd object you might be able to dream up.

Consider the meteoric advance in computer simulation technology: there's little doubt that virtual reality is just around the corner.  A related practice is the design of artificial life simulations.  It is possible that we are all a simulation inside of a giant computer.  Would it not be reasonable to call the creator(s) and/or master(s) of this simulation a god or gods?

The principle of sufficient reason seems to dominate our perception of reality.  It is reasonable to suggest that there might be a first cause or prime mover.  Might this not be God?

The very nature of God is that He is a "higher power" and therefore quite beyond our ken.  It is arrogant and naive to assume that we are the highest level of understanding that this universe has attained.