Yeah, you guys are really oversimplifying the whole "burden of proof" argument. I assume you are (rather incorrectly) referencing Russell's teapot, which does not, as many like to think, state that proof in an unprovable thing is ridiculous. From my rudimentary understanding of Russell's personal philosophy, he was rather defending his own atheism (see: What I Believe, Why I Am Not a Christian) than advocating for all to follow. The direct quote is here :
“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 an intolerable presumption on the part of human reason to doubt it, I should rightly be thought to be talking nonsense. If, however, the existence of such a teapot were affirmed in ancient books, taught as the sacred truth every Sunday, and instilled into the minds of children at school, hesitation to believe in its existence would become a mark of eccentricity and entitle the doubter to the attentions of the psychiatrist in an enlightened age or of the Inquisitor in an earlier time.”
The first sentence is the only one that most people ever pay attention too, and they incorrectly draw from that that Russell is stating the insanity of believing in an improvable concept or object. However, it only states that "nobody would be able to disprove my assertion", not that the assertion itself is faulty. He is merely stating that it is impossible to disprove, not that this impossibility makes the claim itself invalid.
The next sentences tie in the analogy of the teapot with Christianity, certainly, but there is still no direct condemnation of the belief, merely of the lack of acceptance for those who do not believe and the power of cultural and societal norms in enforcing a belief which is neither true nor false - for simplicity, I will now call it "immutable". As I stated previously, Russell's focus was never on providing demonstrable proof of God's nonexistence or stating that a belief in god was nonsensical, merely on defending his own choice to be an atheist.
Furthermore, Russell provides a clear contrast between an immutable belief that is made up on the spot (e.g. the existence of an undetectable china teapot) and one that is steeped on centuries of cultural and societal practices and contains a huge percentage of the population that already believes it. It is precisely this difference between these two claims that is the reason we spend 20 pages on debating the existence of god, not the existence of a china teapot.
It is impossible to determine whether or not a belief in god is "valid" or "justified", but that does not mean that it is not worth analyzing the belief's utility. Branching off of what Myzozoa said, there ARE people who believe in god, and those who do not. It is up to us to determine whether the belief in a god is useful, and from then we can determine whether we should accept the immutability of the existence of god but believe in him anyway (perhaps with nothing more complex than Pascal's wager), to adopt a lifestyle that neither hinges on nor denies the possibility of the existence of god (see that one dubious Marcus Aurelias quote), or to follow Russell and merely accept the possibility but personally hold a lack of belief in the subject. The only beliefs that could theoretically be condemned are those that adopt a stance that denies the immutability of the existence of God - in other words, people who either blindly maintain the existence of God without accepting the possibility of nonexistence, and those that blindly deny the existence of God without allowing for the possibility of his existence. Probability is nigh irrelevant, because attempting to apply probabilistic logic to an improvable statement is impossible.
It follows, then, that the existence of religion is merely a function of the utility that that belief holds. With few exceptions, it appears as though countries with a lower dependence and occurrence of religion tend to be more prosperous and "happy", while poorer countries tend to lean on religion far more. Arguments can be made that this relationship is causal - in other words, that a belief in a higher power or a religion encourages and breeds social problems, poverty, and discrimination etc because of the doctrines and teachings of that religion - an argument that seems to support the "de-proselytization" or spreading of atheism. However, the argument can also be made that this relationship is merely corollary; that as countries "improve", they do not need religion to offer them promise of a good (after)life because their current life is wonderful anyway.
The overwhelming focus on existence on both the religious and atheist sides of this debate is rather ridiculous. The concept of a higher power will always be improvable, and no amount evidence one way or another will change that. The definition of god is inherently fluid and has already proved itself as such, so even an event like, perhaps, determining the exact reason the big bang happened and everything was created etc. etc. would only shift people's definition of god to a more abstract entity, not completely discount its existence. Similarly, no amount of useless posturing by AIG or any other proof-based ontological argument or even the existence of new evidence like a definitive proof of a world flood would change the existence of an inherently immutable concept.
