Paul is providing a prescription for things on which to meditate and thereby nourish our spiritual heart. Just like we need to guard our physical heart in order to keep it healthy, we need to guard our spiritual heart, for whatever dominates our spiritual heart will be reflected in the fruit that we bear in our lives. Jesus told the Pharisees in Matthew 12 that, “A good man out of the good treasure of his heart brings forth good things, and an evil man out of the evil treasure brings forth evil things.”
When we consume a diet heavy in worldly things, then the treasures of God are going to be crowded and pushed out of our hearts. The old adage “garbage in, garbage out” certainly rings true here. Romans 12:2 calls for us to be transformed by the renewing of our minds, and the only way for that to occur is to consume that which is spiritually healthy. Think of the list that Paul provides in our verse today as a grocery list crafted for a healthy diet, and that by adhering to the list, we promote optimal spiritual health. Lord, grant us the desire to fill ourselves with the things of you, and grant that our hearts would be filled with good treasure causing us to bear good fruit in our lives.