Paul's first hint to us that he is addressing a transnational church comes in the greeting he offers in the beginning of all thirteen of his letters. "Grace and peace to you" is a remarkable combination of a Greek salutation charis (grace) and the ancient Hebrew blessing shalom (peace). Grace expresses the joyful fullness of the gospel and peace expresses the fullness of well-being that God desires for us. In this unique greeting, Paul addresses Gentile and Jewish believers together, as members of one church.
Notice that Paul does not write, "Charis to you Greeks and shalom to you Hebrews." Grace is not just for Gentiles and peace is not just for Jews. God desires the whole body of Christ to receive his grace and to experience his peace. Paul writes with respect for his readers' own ethnic and cultural backgrounds, yet he points to a new countercultural reality—a community in which the barriers between Jews and Gentiles is broken down and eliminated.
Writing to congregations that were often divided and torn by factional strife, Paul's greeting is a concrete reminder to believers that they are called to be a "new creation." While affirming the diversity of every part of the church, Paul transcends their differences to forge a new identity. The church is not a congregation created simply by linking Jews and Gentiles together but a united body of Christ, a transformed people made new in the risen Lord.
Stephen J. Binz, Panorama of the Bible: New Testament (Collegeville, MN: Liturgical Press, 2016), 65.