Life in the kingdom is about more than just modifying what you do on the outside.
Jesus wants to change who you are on the inside. The “Pharisees and the teachers of the law” (Matthew 5:20) knew how to look good on the outside, but they were still messed up on the inside. It’s one thing to avoid murdering someone. It’s another to live without even getting angry. It’s one thing to live without cheating on your spouse. It’s another to live without even lusting. If you can get the inside right, the outside will follow.