Why Atheism instead of agnosticism of some sort

[Tiberius]

Richard Dawkins has a scale in the God Delusion about belief, with Gnostic theists ( not the old sect, I mean, as in knowing ) being number one and gnostic atheists at 7. Everything in between is technically some variety of agnostic.

I agree with your post entirely apart from the inclusion of this bit. Dawkins' scale mixes the terms "knowledge" and "certainty" without any regard for what they imply. He also likens a "pure agnostic" (the middle position on his scale) to the belief that "God’s existence and non-existence are exactly equiprobable."

It's a terrible scale for what it is supposed to do. Try this one instead: http://atheistforums.org/thread-3817.html (shameless plug)