It takes cultural isolation and ignorance of the wider world and the gods it already has to invent a new one, and in these times of mass communication and the Internet those conditions are getting hard to find. Give it time though, there will be new ones. There are, for instance, people who believe Elvis Presley still lives and will reappear some day, it's not a big step from there to deifying him. And there are "cargo cults" still extant in the Pacific, building pathetic runways and control towers in the belief that they will once again draw the aircraft full of the magical things that the Second World War brought. It's purely magical--and erroneous--thinking, but it's something people are really good at, there'd be no gods without it.