Of course belief in things that do not exist can have an effect, and poor understanding of the world can seem to have real effects, but that is true of beliefs that almost certainly contradict yours, such as the actions of primitive witch doctors, or the Aztec practice of butchering people with obsidian knives to keep the sun rising on schedule, or the presumption of right wing Christian apologists that the devastation of hurricane Katrina was a statement from God about homosexuality. People can base their behavior on rubbish but that does not make the basis real.