Robert Boyle's treatise, 'On the diversity of religions', remains a little-known work, and was unpublished during his lifetime. Nonetheless it is of considerable historical and philosophical interest. In it, Boyle attempts to answer the question of how one can hope to obtain religious truth amidst the many competing claims to revelation, a concern which had grown acute in the early modern period. In this paper I examine Boyle's arguments, considering along the way their relationship to the various contemporary debates on diversity and evaluating their present relevance.