I came across the concept of egregores on Notes from underground, the blog of an Orthodox anarchist. It seems to me a very useful concept for describing "group mind" - the projection of self beyond the boundaries of the body in order to include others. Sometimes, if the values embraced are liberal, inclusive and humanitarian, such an egregore can be useful; but at other times, it can be destructive and divisive, especially if it involves demonising (projecting a shadow onto) another group.
The clever part about the more inclusive and liberal monotheisms is the idea that there is only one supreme being, who encompasses the whole universe (this is good, because instead of worshipping the egregore of your group, denomination, religion, or country, you are instead worshipping something which is regarded as the parent of all humanity). But the problem of monotheism is that if such a being existed and was omnipotent and omnibenevolent and omniscient as monotheistic religions claim, she would need to be perfect, and not allow evil (such as genocides, pogroms, the Holocaust, etc.) to occur.
Shekhinah theology is quite a good way to account for this problem, but it still does not explain why a perfect being could create a universe in which mind is flawed.
The existence of egregores would certainly account for the narrow, bigoted and sectarian views of many religionists, who are seeking something less than the All - worshipping an egregore of their own cultural values. As Douglas Adams said, many people can't handle the size of the universe, so they choose to live in something smaller of their own devising.
Buddhism has managed to get on for centuries without deities (it acknowledges their existence, but is more interested in liberation from samsara).
Personally I still find Buddhism too interested in liberating spirit from matter, rather than awakening the Mind of the All, but it still has some interesting ideas. That said, if we really want to awaken the Mind of the All, we'd better be sure we give it nice liberal and inclusive values....