This paper is not a formal theological analysis of the Christian doctrine of sin much less an exploration of theological anthropology generally. Its more modest aim is to demonstrate how the use of mathematics as metaphor can be of heuristic value in an effort to understand a theological concept which often seems paradoxical when described in ordinary or traditional language. Given this disclaimer, it is perhaps also useful to make several significant distinctions. Mathematics functions in science as the language of models. It is important for present purposes to distinguish between models and metaphors. Ian Barbour identifies three types of models used in science: experimental, logical and mathematical.[2] The last, he suggests, falls between the first two. A mathematical model "is a symbolic representation of particular aspects of a physical system, and its chief use is to predict the behavior of the latter."[3] As a subclass geometric models are symbolic "pictures" of the relationships of the system. The relationships which are symbolized may be physical or conceptual. A metaphor may be defined as "a figure of speech in which a word or phrase literally denoting one kind of object or idea is used in place of another by way of suggesting a likeness or analogy between them."[4] It is the nature of the metaphor to be both like and not-like the other to which it relates. Part of the power of insight which a metaphor provides derives from this tension of likeness and unlikeness. I am confident that this tension will be evident to theologians and mathematicians/scientists alike as they consider the following. In light of these distinctions this paper is not proposing a mathematical model of sin by which we might be able to predict the moral quality of human behavior. Instead, this paper is proposing a mathematical metaphor which may illumine the conceptual understanding of sin. (James B. Miller)