It happens in marriages, parent-child relationships, friendships, workplaces, and churches: Communication falters, friendships wane, teenagers withdraw, marriages fail, and bitter rifts sever once-strong ties. Christian communities are no exception. Why do so many of our relationships suffer from alienation, indifference, and even hostility?

Author Sam Crabtree believes that often at the heart of these breakdowns is a lack of affirmation. He observes in Scripture that God grants mercy to those who refresh others, and in life that people tend to be influenced by those who praise...