David's heart was ruled by the peace of God when, as a young boy, he faced Goliath in battle. This day will the Lord deliver thee into mine hand . The foes we face in the Christian warfare are stronger and more difficult to defeat than Goliath. Yet in our struggle to overcome, the battle is the Lord's. If the peace of Christ is ruling in our heart, we will leave the battle to the Lord and let him deliver victory into our hands.
Peace is to rule or govern our hearts, our thoughts, our affections and ourway of life.
In the next verse, Paul tells us how to accomplish this. This peace is based on the character and promises of God. For us to have the peace that Peter, Paul and David had, we must remember and keep our mental focus on God and his promises. The peace within our hearts must be expressed outwardly to others. Peace is an especially important characteristic within the body of Christ.