Letter openings in the Hellenistic world followed the formula: “A to B, greeting.” Paul often elaborates on this form. Here “A” is more than one person: Paul, Silas, and Timothy. Any contribution of Silas (“Silvanus,” see Ac 17:1-9; 18:5) and Timothy, one of Paul's co-workers (see 1Co 4:17; Php 2:19-20), cannot be identified.
The epistle is addressed to the church (Gk. ecclesia, “assembly”), the people called into being by God in Christ. The linking of God and Christ shows Paul's high Christology (see 3:11-13).
Into the words grace and peace Paul packs a wealth of theology. Grace is God's love, active in redeeming an undeserved humanity. Peace (Heb. shalom) describes the condition of wholeness that comes from being reconciled to God and therefore with oneself and one's fellows.