During the early 1970s in Ghana, a poster titled “The Heart of Man” appeared on walls and public notice boards. In one picture, all kinds of reptiles—symbols of the vile and despicable—filled the heart-shaped painting with the head of a very unhappy man on top of it. In another image, the heart-shape was clean and serene with the head of a contented man. The caption beneath the images read: “What is the condition of your heart?”

In Matthew 15:18-19, Jesus explained what pollutes a person. “The things that come out of a person’s mouth come from the heart, and these defile…