seriously considering a world without God would probably be a grave sin to begin with
Well, we don’t know the same believers then. The believers I know don’t mind considering a world without God as a thought experiment or as a fiction, and wondering what would happen in such a world (the same way I don’t mind considering a world in which there is a God or magic as a fiction), as long as they keep it clear that it’s “just wondering”. And that could allow them to build a line of retreat.
Well, we don’t know the same believers then. The believers I know don’t mind considering a world without God as a thought experiment or as a fiction, and wondering what would happen in such a world (the same way I don’t mind considering a world in which there is a God or magic as a fiction), as long as they keep it clear that it’s “just wondering”. And that could allow them to build a line of retreat.