3:16 only begotten Son. Jesus calls Himself “Son of man” in John 3:13-14 and “Son of God” in John 3:16-18. As Son of man, He is the “heir” of God’s promises to man (Hebrews 1:2), man as God intended man to be, the perfect man. As Son of God, He is the unique, beloved, only begotten, eternally begotten, Son of the Father, “very God.”
3:17 sent. The fact that God sent His Son into the world is emphasized in many Scriptures (e.g., I John 4:9-10). That He came to save the world from the condemnation it deserved is also confirmed in many other Scriptures (e.g., John 5:24; Acts 17:31; Romans 8:1).
3:18 only begotten. See on John 1:18 for the vital importance of believing in the “only begotten” Son of God. His unique Sonship required the virgin birth, and was proved by the resurrection (Psalm 2:7; Acts 13:33; Romans 1:4; John 5:26).