Peace is a fruit of the Spirit. Among other characteristics, Galatians 5:22–23 lists love, patience, kindness, goodness, and gentleness, all of which must be expressed toward an object. Each piece of spiritual fruit works in concurrence with the others. It's not enough to be kind in one's heart—one must show kindness to others. Peace is no exception. Biblical peace is more than the cessation of hostilities. It is harmony, safety, friendliness, and relational tranquility. Humans are incapable of creating such conditions in their own efforts, as five minutes' viewing of any newscast will prove. Only God can establish peace, and He has done so through the death and resurrection of His Son for forgiveness of sin (Ephesians 2:1–22).
The peace of God begins with God's making peace between Himself and mankind. A true state of peace requires the unity of at least two parties. It also requires sacrifice as self-interest is subordinated to the good of the relationship. The peace between humans and God is no different. God's contribution was to send Jesus, the Prince of Peace, to submit His life (Isaiah 53:5). When we repent and respond in faith to the gift of God, He saves us, and peace is born.
When people are at peace with God, they will also be at peace with each other. Jesus told the seventy disciples, "Whatever house you enter, first say, 'Peace be to this house!' And if a son of peace is there, your peace will rest upon him. But if not, it will return to you" (Luke 10:5–6). If the owner of the home had peace with God, he would naturally be at peace with God's messenger.
Peace with God overshadows conflict in the world. As we allow the Spirit to develop fruit in us, we will have real peace with God and each other.