I would call spirituality in general the 'mapping' of these spaces, descriptions of the way to get there and navigate them, and the preservation of accounts of people who've visited them.

A religion, as I see it, is already focused on one particular version of the map. This can be fine, for example if the particular path is especially compatible with the rest of the culture that's around it. It starts being problematic once it discredits other versions and accounts. Irritating cults is what it becomes when it gets further warped by ego concerns and misinterpretations.