In this episode we look at Robin Dunbar's particular thesis that religion is not just an unexpected outcome of evolution but is, in fact, a mode of engaging with the world that confers substantial benefits on its adherents. We look at the importance of group bonding and the important role that religion plays in this. We talk about why religion is the most effective mode of bonding people in large groups, paying special attention to the role that endorphin release plays in this. Indeed, the emotional background to religion raises interesting questions about the futility of arguing about religious beliefs or trying to reason against religious belief. A big consequence of Dunbar's reading is that one is religious, not for reasons, but because of the emotional pull that religion has over people. Finally, we discuss the role of religion in our increasingly secular societies. If religion is as important to group bonding as Dunbar would argue, then what does this mean for the decline of religion that we are witnessing across the Western world? We discuss all this, and more, in our thought-provoking interview with Robin Dunbar.