Here's a picture of a phylogenetic tree based on the evolutionary history of world religions (note that it's inaccurate to some extent):
Evolutionary Phylogeny of Religion
Based on this scheme, the myriad of major monotheistic religions share a common ancestor as do the polytheistic religions of Europe/Middle East/India. Of course deciding whether one religion is the same species as another depends on if you're a lumper or a splitter. I'm definitely a lumper and classify them all as superstition.
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