Christianity concerns itself with salvation. But salvation implies something from which one must be saved, as reconciliation implies an estrangement and redemption a loss. The classical theological symbol naming the problem to which salvation is the solution is sin. Interpreting the meaning of sin, however, has become difficult for two reasons: sin has become a taboo subject in popular discourse, and has acquired an extremely broad meaning in recent theology.    Sin: A Guide for the Perplexed is intended as a mid-level, comprehensive introduction to the notion of sin and its significance for Christian theology. Nelson situates and interprets biblical material on sin, and then offers a lucid history of the doctrine. He elucidates Augustine's conception of original sin and defends it against its many caricatures. Special attention is paid to sin as an ordinary, yet highly interruptive, phenomenon in the lives of individuals. This is supplemented by a careful look at the non-individualistic dimensions of sin, and an appreciation of how sin relates to other key theological commitments.