This book consists of the Gifford Lectures, given in the University of Glasgow in 1993–4, and of the Selwyn Lectures, given at St John's College, Auckland, in 1993. I owe a great debt to all who heard and commented on them in their spoken form. Relevant parts of the text have been read by specialist colleagues at Oxford, and I would particularly like to thank Ron Nettler, Julian Johansen, Peter Clarke, and Peggy Morgan for their advice. They have been unable to cause me to give up some of my ideas, but have at least saved me from making reprehensible errors and inaccurate generalizations, especially in dealing with non-Christian traditions.

Most of all, my wife Marian, by her continual support and criticism, has made this a much more readable and ordered text, and I dedicate it to her with love and gratitude.

K. W.