It is not unreasonable to think that "God is less likely than Russell's teapot", but it is definitely unreasonable to say "I am sure god does not exist" since, by definition, god is untestable.
I guess that what I am trying to say is that a "strong atheist" (with judgements based on reason), can not really assert with 100% confidence that god does not exist. He can, nevertheless, be convinced that the likelihood of its existence is for all practical purposes 0.
It is not that he "believes that god does not exist", it is more that he thinks along the lines of "why should I care about this particular teapot?"
It is that he believes that God does not exist, in that he asserts that the probability of God is substantially less than the probability of no God. In the same way that he believes that, having looked both ways and seen no car, he won't be hit by a car when he's crossing the street (though I'm not asserting any relationship between the magnitude of the respective likelihoods). There's the possibility he's wrong, and that'd be unfortunate, but it's what he believes in that it's what his understanding of the world says and it's what determines his actions. Using the word "atheist" for such people seems entirely reasonable. Most of them will agree that they are, in some senses, strictly agnostic as well - the categories needn't be mutually exclusive.
I guess that what I am trying to say is that a "strong atheist" (with judgements based on reason), can not really assert with 100% confidence that god does not exist. He can, nevertheless, be convinced that the likelihood of its existence is for all practical purposes 0.
It is not that he "believes that god does not exist", it is more that he thinks along the lines of "why should I care about this particular teapot?"