This article sets out a formal procedure for determining the probability that God would do a specified action, using our moral knowledge and understanding God as a perfect being. To motivate developing the procedure I show how natural theology - design arguments, the problems of evil and divine hiddenness, and the treatment of miracles and religious experiences as evidence for claims about God - routinely appeals to judgments involving these probabilities. To set out the procedure, I describe a decision-theoretic model for practical reasoning which is deontological so as to appeal to theists, but is designed not to presuppose any substantive moral commitments, and to accommodate normative and non-normative uncertainty. Then I explain how judgments about what we probably ought to do can be transformed into judgments about what God would probably do. Then I show the usefulness of the procedure by describing how it can help structure discussions in natural theology and a-theology, and how it offers an attractive alternative to 'skeptical theism'.