Flat Earth and Geocentrism

[Sword of Christ]

And if they didn't come out of that process as an atheist, or at least an agnostic, they failed to be reasonable.

No they succeeded to be reasonable and there were people outside of the Christian, Jewish or monotheistic context who managed to do the same thing and draw the same conclusions using the same logic. You can't figure out redemptive atonement from sin through Gods saving grace through reason alone though you still need the Bible to give the juicy info on that.