This article explores the implications of the social brain and the endorphin-based bonding mechanism that underpins it for the evolution of religion. I argue that religion evolved as one of the behavioural mechanisms designed to facilitate community bonding when humans first evolved the larger social groups of ~150 that now characterise our species. This is not a matter of facilitating cooperation, but of engineering social cohesion – a very different problem. Analysis of the size of C19th utopian communities suggests that (...) a religious basis both allowed larger groups to form and greatly enhanced their longevity. I suggest that religion evolved in two stages: an early immersive form with no formal structure based on trance-dancing (a form still evident in the rituals and practices of many hunter-gatherers) and a later form which had more formal structures and gave rise to our modern doctrinal religions. I argue that the modern doctrinal religions did not replace ancestral immersive religions but rather that the doctrinal component was overlaid on the ancient immersive form, thereby giving rise to the mystical stance that underlies all world religions. I suggest that it is this mystical stance that causes the constant upwelling of cults and sects within world religions. (shrink)