Friendly Atheism

[John 6IX Breezy]

If we're allowed to think of this in relation to other times and other cultures, then I think theism is often rational. 

If you grow up in a society in which all accepted explanations of things are woven into the religious views, and all the sane successful adults hold these things to be true, it would be arbitrary and irrational to reject theism. 

I think that an educated person in Paris in the 13th century would be entirely reasonable to be religious, without question. In the 21st century, it depends more on the metaphysics he has, which are not as self-evidently in sync with everything else in the world.

I agree; although you seem to place more emphasis on the context than the subject compared to me, but both go hand in hand. It reminds me of William James (1896) notion of live vs dead hypothesis. A hypothesis is live when it appears as a real possibility to someone's mind, and it is dead when it does not. So to use your example, geocentric beliefs might be a dead hypotheses to most of us because it isn't among our minds possibilities, but to someone living during that era the hypothesis was live. Christian beliefs might be a live hypothesis to people in America but it is dead to those living elsewhere.

An important point he mentions on the matter is that liveness or deadness are not intrinsic qualities to these hypothesis, they are subject-dependant, being alive or dead only in the person's mind. Perhaps we can add that live hypothesis appear rational to the one for whom it is live, and dead hypothesis apear irrational to the one for whom it is dead.

Reference: James, W. (1896). The will to believe: And other essays in popular philosophy. A Public Domain Book.