Is a religious naturalism possible? 'Scientific' naturalism accommodates only 'thin' religiousness. A more robust religious naturalism posits an ultimate reality that supports the ideals of eco-morality and the hope that human fulfilment may be achieved by following those ideals. Such an account may yet be 'expansively' naturalist in taking the natural world to be the only (concrete) reality, and in not going against, only beyond, well-confirmed science. For the core content of an expansive religious naturalism, this Element proposes the idea of an inherent integrative cosmic purpose. The authors reflect both on Indigenous worldviews and on theist traditions in pursuing this proposal. This title is also available as open access on Cambridge Core.