In one of his late notebooks containing remarks on the philosophy of psychology, Wittgenstein states in passing: ‘If someone can believe in God with complete certainty, why not in Other Minds?’ (MS 137, 67a). In this paper, I introduce and explain some of the assumptions and observations behind this remark. In doing so, I give an example of what I describe as an ‘indirect or derived philosophy-of-religion reading strategy’, which highlights some of Wittgenstein’s very late thoughts on the grammar of religious belief and language. The crucial observation in Wittgenstein’s remark is the existence of a family resemblance between ‘the foundation’ of the religious attitude and belief on the one hand, and the complex ‘pattern of our experience that is hard to describe’, and which forms the basis of our reactions to and understanding of other persons’ behaviour and psychical states (MS 174,2) on the other. Thus this paper draws attention, firstly, to the fact that, in his late work, Wittgenstein emphasises that our use of concepts to determine other people’s feelings and states is comparable to certain religious uses of language, and secondly, to some of the familial connections between these uses of language.