There is an ancient Christian saying from the Patristic Era which is known in its most concise form as lex orandi, lex credendi. As the Catechism of the Catholic Church translates it: “The law of prayer is the law of faith: the Church believes as she prays.”

In 1980, two men sit down to record a conversation. They have much in common: both are passionate, articulate thinkers. But their differences are just as striking….