C.S. Lewis’s ‘Argument from Desire’ is best summed up by his famous line, ‘If I find in myself a desire which no experience in this world can satisfy, the most probable explanation is that I was made for another world’. In short, unfulfilled ‘seemingly transcendent desires’ point to fulfilment in another realm. Lewis’s argument is fraught with disagreement, and subsequently, questions remain as to its efficacy as a theistic argument. In this essay, I will take a novel approach by using Bayes’ theorem to assess the success of Lewis’s argument in support of theism over and against naturalism. As I will argue, a strength of this approach is that it allows me to largely bypass a significant area of disagreement within the literature, namely, whether these desires are best seen as natural or artificial. Additionally, I will argue for why these desires are the sort of good God would be interested in giving to persons. Then, I will proceed to outline what I take to be the best naturalistic accounts of these desires and outline some of the challenges these accounts face. Finally, I will conclude with plugging these results into Bayes’ theorem.