What central case of religion fails to meet these three conditions? Some forms of Buddhism may be non-theistic but they still I think recognize non-natural events or states of affairs, e.g. reincarnation.  I suppose there's the question of what constitutes an "institution" but being fairly liberal about that so that institutions don't have to be centralized I think congregationalist and non-hierarchical religions count as embodied in institutions: as long as you have some bureaucrats or administrators dealing with finances and logistics that's good enough to count as an institution. Then there's the question of what sort of activities constitute ritual. Well we know it when we see it. But on the account I'm suggesting ritual is the primary religion-making factor. And ISN'T this the way the folk see it?