“‘Belief or Nonbelief’ is a short but challengingbook, an exchange of letters between Umberto Eco, the Italian novelist and scholar, and Carlo Maria Martini, the Roman Catholic cardinal of Milan. A newspaper in Milan asked the two men to write to each other (and published the results) because they represent the believer and the nonbeliever, the Catholic and the secularist, the one who left the church and the one who stayed. The result, says Harvard theologian Harvey Cox in his introduction, is a “My Dinner With Andre” on paper, a conversation between two amazing minds on which we have the luck to eavesdrop…. In an age of talk radio’s ugly rejoinders and the weak-kneed compromise we all tend toward in order to get along, this robust exchange is a joy to read.”