For those who did not grow up with the historic Christian liturgy, the passing of the peace before communion appears to be a fancy form of the “greet your neighbor” portion of the modern evangelical worship service. In evangelicalism, the purpose for greeting one’s neighbor is twofold: 1) make newcomers feel welcome and connected so that they return and eventually join the church; and 2) give friends a time to say hello to each other. The second purpose seems to predominate; the “meet and greet” at the beginning of worship could go on forever when friends chat in the aisle.
The passing of the peace before communion shares some characteristics with the evangelical greeting ritual: it is a greeting, and usually involves shaking hands. The similarity, however, ends there.
In the historic liturgy, the offering of peace to each other does not come at the beginning of the worship service, but before the offering and the Eucharistic prayer. It comes after the reading of the scriptures and the preaching of the sermon. In other words, we offer our peace to each other in response to God’s word. Our peace is not the natural state of affairs; it exists only because it has been created by the word of God, and by what God has done for us in Jesus Christ. When we offer peace to each other, it is an act of faith, believing that God has called and empowered us to do this.
The greeting of “Peace” has its roots in the ancient Hebrew greeting of “Shalom.” The Hebrew word encompasses a wide variety of meanings: peace between people or nations, peace between God and human beings, human welfare or well-being, safety, or a quiet, restful state of mind. Shalom is “wholeness,” a life where things are as they should be. The church took over the greeting of peace (eirene in Greek, pax in Latin) from its Jewish forebears, and Islam carried it into Arabic: as salaam alaikum. At its most basic, when people greet one another with the word “peace,” it means “you don’t have to be afraid of me and I wish for your well being.”
“Peace” became a common Christian greeting very early in the New Testament era. The oldest Christian document in the New Testament is a letter (1 Thessalonians) in which Paul begins, “Grace and peace to you.” Peter, Jude and the author of Revelation also begin their letters with greetings of peace. Paul starts most of his letters this way, usually adding “from God the Father and the Lord Jesus Christ.” While Christians share the greeting of “peace” with our Jewish kinfolk and our Muslim neighbors, we understand it in a way that they do not. Peace is a gift of God the Father given through the Lord Jesus Christ. The peace that we wish for another is rooted in the one who is himself our peace.
In fact, when we say “Peace be with you,” we are saying the very same words that the risen Jesus said when he greeted his disciples after the resurrection. Through the power of the Holy Spirit, Jesus once again speaks through us these words of blessing and comfort.
By using this ancient and biblical greeting in our worship, we are saying that we aren’t just any group of people who happen to be meeting together as friends. We are the church of Jesus Christ. Our unity – our peace – is not rooted in the fact that we happen to like playing golf together or our kids are on the same soccer team or even in our ordinary human friendships; we are together as brothers and sisters in worship because of and through Jesus Christ. When we gather as the church to worship, even our greeting reminds us of the basis of our union with each other in this place.
In fact, the greeting of peace moves us beyond ordinary human friendships. We give the same greeting of peace to those to whom we feel close, and to those we don’t. Before we come to the communion table, we even offer the greeting of peace to those who might be our enemies. Jesus said,
If you are offering your gift at the altar and there remember that your brother or sister has something against you, leave your gift there in front of the altar. First go and be reconciled to them; then come and offer your gift. (Matthew 5:23-24)
When we greet each other in peace before we share communion, we are fulfilling Jesus’ command. We only offer our Eucharist – our offering of praise and thanksgiving – after we are reconciled to each other. The fellowship of the table is not only a sign of peace between God and his people, it is also a sign of peace among God’s people. To come to the table without reconciling oneself with one’s neighbor is a sham.
So sometimes “passing the peace” can be a little uncomfortable. It can remind us of how broken and incomplete our relationships with our brothers and sisters really are. We can and should offer peace to another, not based in our natural human emotions or affections, but in faith that Jesus has indeed established peace for us and among us. Faith drives us to live in that peace and claim that peace, even if we don’t feel it and even if in our sinfulness we sometimes fall short of it. To greet one another in peace is an act of faith, and it should compel us to make that peace more real among us.
Finally, the peace is not just a greeting we share before we come to the table, it is a priestly blessing that we offer each other. In the liturgy, the sharing of peace not only precedes the offering of the Eucharist, it concludes the prayers of the people. In pronouncing peace upon each other we are, in effect, praying for each other. We are asking God to give peace, in all its fullness, to our brothers and sisters in Christ. “Peace be with you” is a blessing that we pronounce in the name and power of Jesus Christ, risen from the dead. All of the baptized are members of a “royal priesthood,” called and empowered by the Holy Spirit to offer the blessings of the risen Christ to the world.
The peace of the Lord be with you.
Related:
Peace Be With You
Mitchell Lewis 
The Passing of the Peace also served as a historic time of transition and dismissal. After the sermon, catechumens would leave the service to receive instruction as they weren’t allowed to receive the Lord’s Supper anyway. The Passing of the Peace served to move the service from Word to Table.
It’s kind of like how kids are sometimes sent off to Children’s Church during a hymn, but with more symbolic importance and less “getting those noisy young ‘uns out before the sermon.”