The Karl Rahner name on any book commands the attention of serious scholars. But in recent years his appeal has been extended to men in all walks of life, particularly the educated laity. The thesis of this present work, therefore, should be especially welcome since it addresses itself to the role of the Christian today. Though speaking as a theologian, his message is clear and urgent. Father Rahner demonstrates that Christianity is the most reliable recipe for a happy life precisely because it is achievable only if one does not care whether this is so or not. In what he calls the ""diaspora situation"" of modern living he insists that one cannot just be Catholic by culture, by politics, or by civic morality without belief in the eternal life and in the promise of God. This expert's admonition to attend to the ""Christian Commitment"" is forceful argumentation which cannot be easily ignored by the intelligent reader. Father Rahner offers new insights to Church-old formulas opening a way to aggiornamento to all Christians in a modern age.