What does Matthew 16:12 mean?
Finally, the disciples understood their mistake (Matthew 16:5–11). We might be tempted to laugh at them so thoroughly missing the point. We can overcome that temptation by remembering all the times we have been so focused on our own anxiety that we missed what God was clearly showing us. Human anxiety is normal, which is why Scripture so often seeks to reassure us (John 16:32–33; 2 Corinthians 5:6). But worry is also distracting; the more readily we trust God, the more easily we accomplish His will (Matthew 6:33–34).The disciples now know Jesus was not talking about food. He was not upset they didn't pack bread for their trip. He was not worried about what they would eat. He wanted them to be aware of the false teaching of Israel's religious leaders, and of those who use false assumptions to undermine the truth. This "leaven," which can infect a person's entire belief system, would become a life-and-death issue for Jesus and His followers.