“You are my Son…” was the Father’s voice from heaven. Jesus own assertion and intimation indicate that references to Him as Son of God can be traced to Jesus Himself. At the center of Jesus identity in the fourth Gospel is His divine state as Son (John 10:36). Jesus conceived of His divine state as Son as unique as indicated by such assertions as “I and the Father are one” (John 10:30 NIV) and the Father is in me and I am in the Father” (John 10:38 NRSV). Elsewhere, He frequently referred to God as my Father (John 5:17; 6:32; 8:54; 10:18; 15:15; Matt. 7:21; 10:32-33; 20:23; 26:29,53; Mark 8:38; Luke 2:49; 10:21-22).
At Jesus baptism and transfiguration, God the Father identified Jesus as His Son, in passages reflecting Psalm 2:7. He was identified as Son of God by an angel prior to His birth (Luke 1:32,35); by Satan at His temptation (Matt. 4:3,6); by John the Baptist (John 1:34); by the centurion at the crucifixion (Matt. 27:54). Several of His followers ascribed to Him this title in various contexts (Matt. 14:33; 16:16; John 1:49; 11:27).
The term Son of God reveals Jesus’ divine Son-ship and is closely associated with His royal position as Messiah. Gabriel told Mary that her Son would not only be called the Son of God, but would also reign on the Messianic (David’s) throne (Luke 1:32-33). The connection of Son of God with Jesus’ royal office is also found in John (1:49; 11:27; 20:30), in Paul (Rom. 1:3-4; and 1 Cor. 15:28; Col. 1:13), and in Luke (Acts 9:20-22).
Primarily, the title Son of God affirms Jesus deity evidenced by His person and His work. John emphasized Jesus personal relationship to the Father. Paul stressed the salvation that Jesus provided (Romans 1:4; and 1 Thessalonians 1:10), and the author of Hebrews focused on Jesus priesthood (5:5). All of these are vitally related to His position as Son of God. (David S. Dockery -Holman Bible Dictionary)
