Falling down doesn't require belief. At least not in the sense that most people understand belief. If it did, then falling down would be a religion. But it doesn't, so it's not.

But there is no more evidence of the absence of a god than there is of the existence of a god, so people who believe there is or isn't, and who have stuck a name on their belief, and who must share the belief in order to apply the name to themselves, are religious people.

Religion (from Wikipedia):

A religion is a system of human thought which usually includes a set of narratives, symbols, beliefs and practices that give meaning to the practitioner's experiences of life through reference to a higher power, deity or deities, or ultimate truth.