As a reporter at the Chicago Tribune, I was assigned to write a series of articles profiling poor families in Chicago. My research took me to a shelter run by the Salvation Army.

For weeks, I observed as volunteers tended to the homeless and destitute—people that nobody else seemed to care about. They provided food, housing, clothing, and counseling. They helped them find jobs. They calmed their frightened children.

At the end of my research, I stopped to say good-bye to the woman in charge. During our chat, she said. "Lee, I know you're a skeptic, but I'm curious. What do you think about Jesus?"

An adamant atheist at the time, I was accustomed to shutting down Christians who tried to proselytize me. Yet when this woman started talking about God, I was suddenly receptive. Why? Because she wasn't just telling me that God loves people; I had seen her and her team living out that value through their selfless acts of service.

Watching them express God's grace to hurting people had started ...