"it occurs to me that the concept of religion is not confined to humans."

Actually, Musket, you've stumbled on a great truth there. All of Nature salutes the sacredness and holy power of existence every day, each animal in their own fashion, some with quite dramatic forms of ritual, generally around either sunrise or sunset, depending on whether they are nocturnal or diurnal creatures. In doing this, they are behaving in a profoundly religious manner...and they're actually far more tuned in than most people are (because their heads aren't so full of extraneous stuff as ours are).

I've witnessed it many times in Nature. It's particularly noticeable with birds, coyotes, wolves, and dogs, but pretty well all animals evidence it to some extent.

And they need no Bible and no Church to do it, but they are acknowledging something quite holy by pure instinct and awareness. I think that "something" is the same thing people seek out in religion...we just dress it up in far more complex clothing, so to speak...and it's the very specific forms of clothing that you object to. ;-D