Agnostics are atheists who haven't come out of the closet yet. Think homosexuals in the 1950's.
Either that, or they are 99.9999999% sure there is no god, but they are hedging their bets "just in case"
I think agnostics are gutless, and I probably have more disdain for them than I do for "true believers". Theists (in whatever denomination) just don't know any better, which is sad, but more palatable than people who profess to be agnostic or theists for public consumption but know better.