A prominent historian investigating the death of Jesus experienced a conversion — and a brush with the supernatural

It was July in 2016, and Holland was in the northern Iraq city of Sinjar. He had arrived with a BBC film crew about three months after ISIS, the murderous jihadist group, had tried and failed to retake the town after massacring members of the Yazidis, an ancient religious and ethnic minority in Iraq. Holland knew something about ancient history. He was an award-winning British historian who had written popular books about ruthless Spartan and Roman leaders he called the “apex predators” of the Greco-Roman world. They lived by the Athenian dictum: The strong do what they can and the...