Why God?: Explaining Religious Phenomena

Why is it that the majority of people, from all socio-economic, education, and ethnic backgrounds, ascribe to some sort of faith? What draws us to religion? What pushes us away? And what exactly is religion anyway?
Defining religion over the past century has, ironically, led to theories that exclude belief in God, proposing that all systems of thought concerning the meaning of life are religions. Of course, this makes it impossible to distinguish the village priest from the village atheist...