Peter van Inwagen has written a response to Bertrand Russell's teapot argument (H/T ex-apologist) in which he assures us that there are people who accept the following two propositions:
(1) There is no reason to believe that God exists.
(2) Any one who accepts (1) should conclude that the probability of the existence of God is essentially 0.
He offers Russell's teapot argument as an example. However, while Russell clearly accepts (1), there's no discernible evidence that Russell ever endorsed anything like (2). In the essay which van Inwagen cites ("Is There A God?", Russell, 1952), Russell argues that a divine purpose is improbable (on the scientific evidence) and thus that there is no reason to believe in a God. He deduces the latter from the former, not the former from the latter. Furthermore, his teapot argument is offered to a different purpose altogether.
Here is what Russell writes, and what van Inwagen quotes:
Many orthodox people speak as though it were the business of sceptics to disprove received dogmas rather than of dogmatists to prove them. This is, of course, a mistake. If I were to suggest that between the Earth and Mars there is a china teapot revolving about the sun in an elliptical orbit, nobody would be able to disprove my assertion provided I were careful to add that the teapot is too small to be revealed even by our most powerful telescopes. But if I were
to go on to say that, since my assertion cannot be disproved, it is intolerable presumption on the part of human reason to doubt it, I should rightly be thought to be talking nonsense.
Russell's teapot argument is that the burden of proof regarding the existence of God is on the people who claim that there is a God, and not on the skeptics. There is no burden to disprove God, since there is no reason to believe in God in the first place. The conclusion of the teapot argument is not that God's existence is highly improbable, but that theists are wrong to criticize non-theists for being skeptical.
Russell never assumes anything like (2). In fact, it's not clear that any philosopher of note has ever endorsed (2). So I am really not sure why van Inwagen has written a paper about it.
P.S. I've critiqued Russell's teapot argument, too, but on very different grounds: Why I Am Not A Teapot Agnostic.