This part introduction presents an overview of the key concepts discussed in the subsequent chapters. The part examines the religious form of life within which the language game of prayers makes sense. It was originally written in Dutch as a contribution to a symposium on dialogue between Christians and Jews on the nature of prayer. The part distinguishes between these differences in mysticism and shows that religious believers derive their personal identity and their intrinsic value as individuals from their loving fellowship with God. In this sense believers seek and find ultimate happiness in such fellowship with God. There are many kinds of mysticism and most mystics seek personal fellowship with God rather than merging with the Divine. The part discusses strict determinism is incompatible with the ideal of loving fellowship with God since the latter presupposes that both partners in the fellowship are free personal agents