Dr S,
Good argument !
I seem to be forever doomed to repeat (like the Ancient Mariner
) that the central issues in this question are ontological and epistemological ones: namely (1) what do we mean by "exist" and (2) how we distinguish between "knowledge" and "belief". I adopt a "social reality" position with respect to these issues which leads me to the conclusion that agnostics simply don't seem to understand these issues at all. Theists cash in on the blurred boundaries between knowledge and belief in favour of "knowledge of God" and "straight" atheists tend to take arguments such as your own above as glaringly obvious.
I call myself an atheist, but for me each of the labels is
actually significant only in terms of its social consequences i.e. "bias towards social action". In this respect I agree with those who see theism as pernicious, and agnosticism as social inertia or misplaced political correctness. And for those who would argue that "atheism" has been shown to be a disasterous social force itself I would point out that its manifestation as "communism" had all the aspects of "religion" in that it replaced celestial "deities" with earthly ones. The masses exchanged one opiate for another. Unfortunately it may be the case that the average human psyche will be forever prone to such opiates.
As for whether "agnosticism" is rational", this depends on how we interpret the word "rational". Since there are problems in equating "rationality" with "logicality" I would argue that rationality is a "coherent framework for viewing ones place in the world". So perhaps we could argue that agnosticism is "irrational" because such a framework is lacking.