Such a topic as this raises problems. Both Judaism and Christianity consist of a spectrum of organisations loosely associated with each other within a broad tradition, rather than neat, consistent, homogeneous religions. There is also the problem of understanding the thinking of people living in past eras and other cultures, especially as religions tend to behave as if events and experiences from the distant past—complete with detailed laws—still apply with all the force of divine authority. It will be an achievement just to identify a credible method for handling a topic such as this.

To start at all we must have a working definition of sin, whatever the difficulties, so the working definition is: ‘Sin is whatever is thought to ignore or defy God’s revealed will’. Some of the consequent questions are: How is God’s will revealed? What does it reveal? What constitutes defiance of it? Most of what follows looks at some of the answers given by Christians and Jews at various times. Finally, a conclusion is reached about common elements in what Jews and Christians understand by ‘sin’, and how to talk about it. Like all true mysteries, sin cannot be described comprehensively, but this does not mean that we have to retreat into silence. There is a way of talking theology which preserves integrity.

Both Jews and Christians share common ground in their belief that what Christians call the Old Testament contains the revealed will of God, even though Christians then modify their attitude towards the Old Testament in the light of what is contained in the New Testament.