I honestly can imagine few things more childish than believing that having the local shaman uttering a few words of mumbo-jumbo will turn bread and fruit juice into the spirit of the Almighty Creator of the Universe (whom the worshippers then proceed to consume!) and ridiculing such superstitions is the job of responsible adults in teaching people to, in Paul's words, "put away childish things."
Were a South Pacific tribe reported to believe that saying a few words over mango pulp would turn it into the Great Spirit of the Sky, I have no doubt that most Christians would snicker at how 'primitive' the natives were for holding to such ideas. True puerility is refusing to recognize one's own superstitions as such.