Once upon a happier time, when the Middle East seemed more distant but less dangerous than it does today, I flew from London to Riyadh on Saudi Arabian Airlines. It was shortly before the beginning of Ramadan, and the plane was full of pilgrims making the most important journey of their lives.

The 747's television screens offered the usual array of information about our journey: a frequently updated map showing the location of the plane, our current speed, the alarmingly frigid temperature at our cruising altitude. But they also displayed a compass, with a silhouette of an airplane and a mark indicating the Qibla, the direction of Mecca.

My fellow travelers had boarded wearing Western clothing or the traditional dress of various countries of the Muslim world. But by mid-flight nearly everyone had changed into white ihram garments, the simple unsewn clothing of pilgrims. A few at a time, they laid down their prayer rugs in the economy class galley, the flight attendants respectfully making room, and offered their prayers toward Qibla. I watched two twentysomething parents make their way to the galley and pray with their six-year-old son, instructing him gently and quietly. Their faces were shining: a family on pilgrimage, all in white.

Jesus once met—or, actually, didn't meet—a Gentile whose faith made a deep impression on him. A Roman centurion in Capernaum sent the local Jewish elders to ask Jesus to heal his servant, but when Jesus approached his home the soldier sent more messengers to say that Jesus' presence was unnecessary. Jesus' word would be enough: "For I myself am a man under authority, with soldiers under me. I tell this one, 'Go,' and he goes; and that one, 'Come,' and he comes. I say to my servant, 'Do this,' ...