While there may be cases in which cohabitation is a venial sin, the professor continued, it is "always grave matter."
"It could in some cases not be accompanied by sufficient knowledge and/or freedom to make it a mortal sin," Miller acknowledged. But even so, it is a separate question whether defenders of the controversial interpretations of Amoris Laetitia have made a good case about what circumstances "would in fact amount to a lack of sufficient freedom."
Cardinal Kasper's interview reflected on the results where some parishes have meetings with spouses or engaged couples in which they read part of Amoris Laetitia.
"This document's language is so clear that any Christian can understand it," the cardinal said. "It is not high theology incomprehensible to people. The People of God are very content, and happy with this document because it gives space to freedom, but it also interprets the substance of the Christian message in an understandable language."
He said this shows "the Pope has an optimal connection with the People of God"
Cardinal Kasper's remarks also reflected on the importance of mercy.
"Today we are living a violent time which has never before been experienced," he said. "Many people are wounded. Even in marriages there are many who are wounded. People need mercy, empathy, the sympathy of the Church in these difficult times in which we are living today. I think that mercy is the response to the signs of our times."
Miller found truth in these comments.
"St. John Paul II spoke of mercy as the limit God puts on evil," he said. However, the professor suggested there is a "more complex" relationship between mercy and empathy.
"For the Church, there is not even tension, let alone opposition, between mercy and truth each authentically understood," Miller said. "Mercy, insofar as it is a reality in God's saving plan, is part of the truth. Truth, insofar as it sets us free for sharing in God's life and happiness, is mercy."
There are ways of presenting truth that are more or less merciful, he noted, adding "But withholding the truth about God's loving and transformative grace and law is not merciful either."
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Cardinal Kasper's interview reflected on the necessary role for debate in the Church.
"There is no need to fear debate!" he said. However, there is now "a very bitter debate, way too strong, with accusations of heresy."
"A heresy is a tenacious disagreement with formal dogma," he said. "The doctrine of the indissolubility of marriage has not been called into question on Pope Francis' part!"
The cardinal said that before any such accusation of heresy, "the question should be what the other person means by what has been said."
"And, above all, that the other person is Catholic should be presupposed, the opposite should not be supposed!" he emphasized, in an English-language translation of the Vatican News interview.
Vatican News reported the Kasper interview in several languages, while also posting audio interviews with the cardinal in different languages. Some audio versions include comments expanded beyond the reported text.