God promises eschatological outpouring of the Spirit in passages such as Joel 2 and Ezekiel 36.
Joel 2:28-32 and Ezekiel 36:25-27 provide important Spirit-outpouring background.
Jesus is not merely Spirit-anointed; he is identified as the one who gives the Holy Spirit, a role fulfilled again in John 20.
Giving the Spirit and possessing unique divine sonship together contribute strongly to John's presentation of Jesus' identity and authority.
John bears witness to what God had revealed to him about Jesus.