Eugene Volokh has a post explaining how references to pagan gods evade the establishment clause. It makes me wonder: wouldn't a way around the current concern about the pledge of allegiance be to change the awkward phrase to "...one nation, under Gods, with liberty..."?

This would be MORE inclusive, it shouldn't offend the sensibility of monotheists any more than the current pledge offends the sensibility of atheists, and ought to be ok with the establishment clause, to boot.