Friedrich Heiler, Sadhu Sundar Singh Ein Apostel des Ostens und Westens (Munchen: Verlag von Ernst Reinhardt, 1925).
When Sundar Singh’s mom died, the boy raged against the God of the Christians for, although a Sikh, he was being educated at a Christian school. Just fourteen years old, he formed a gang which harassed and persecuted believers. He burned a Bible to show his contempt for Jesus.
Children’s Heroes From Christian History: Vol. II includes stories on four heroes: William Carey, Robert Raikes, Hans Egede and Sundar Singh. Recommended for ages 5–10.