You mentioned that your stance on the Biblical God is based "only on the balance of probabilities". I think that's a wise thing to acknowledge, however, I'd even take it a step further. I'd argue that it's in fact a tautology. Because in the end, everything any of us believe is only on the balance of probabilities - it's not just true of our belief or disbelief in God.

In that vein, I also don't think my 'Oz' analogy can be dismissed so easily just because it claims to be fiction. A fiction who's author acknowledges it as such, and a fiction who's author claims it to be true, are only marginally different - not categorically so. All other things being equal, purported truths probably tend to have slightly higher probabilities of being true than admitted fictions. But the intentions of the author is just one of many things to take into account when assigning an overall probability to a claim.

The concept you mentioned of a "lie we're comfortable with" is a useful one. "The Earth is round", and "the Earth revolves around the Sun" are also lies that we're generally comfortable with. Because they seem highly likely to be true. Or perhaps more accurately, because they seem highly likely to be useful. Because if we're truly sticklers with our claims, we must admit that the "truth" is so far out of reach, that it's not even something we can honestly strive for. Instead, we have to strive for the next best thing, namely, that we make claims that are useful.

And that's where atheism comes in.

Atheists don't think belief in God is a useful claim. And in fact, most think it is a harmful claim. And if belief in the God of Abraham is a harmful claim, perhaps claiming the nonexistence of that God is in fact, a beneficial - that is, a highly useful - claim. That's certainly what I think.

So in the same way that "the witch and the monkeys aren't real" is a lie that we're comfortable telling a frightened child, I think "there is no God of Abraham" is a lie that we should be comfortable with telling to any capable adult.