In October 2011, Professor Moltmann, in Atlanta to lecture at Emory, asked Professor McBride if he could visit Ms. Gissendaner in prison. His visit coincided with a graduation ceremony for the 10 or so theology students at the prison, and he agreed to give a commencement address.

After the ceremony, “the three of us sat together,” Professor McBride recalled. “They talked about their mutual experience in prison, and about how they both had time in the military” — a German soldier in World War II, Professor Moltmann was a prisoner of war afterward. “They talked about what it was like to read the Bible in prison.”

Ms. Gissendaner began her studies while at Metro State Prison, near Atlanta. At first, she studied with her classmates. But halfway through her yearlong program, a new prison administration would not let her out of her cell for coursework. To continue her studies, her teachers would visit her.

“We came to her and taught theology through the bars of her cell,” Professor McBride said. “So I had one-on-one time with her for about two hours, every Friday, for six months.”

Metro closed, and Ms. Gissendaner was moved to Lee Arrendale State Prison, in Habersham County, where she was allowed to sit with her teachers in a visiting room. Professor McBride soon moved to Iowa. In a letter dated Feb. 10, 2012, Professor Moltmann wrote that he was concerned, not having heard from Ms. Gissendaner “for quite a while.”

“Dear Kelly,” he wrote, “Friede sei mit dir” — peace be with you. He was enjoying “Journey of Hope by Faith,” the devotional book she had written as a final project for her theology certificate; it gave him “much inspiration.”

“Can you continue your theological studies?” he asked. “Who is in charge now since Jenny left? I am still studying theology with 85 years and discover new ideas. It is an adventure of ideas, not only faith. Theology is to love God with your mind.”