Great God. Declaring the Name of God and the wondrous works of God. God as Creator, Sustainer, Judge and Savior. Praising God for what He does and for who He is. Declaring the true God, the biblical God, among the nations. Lifting up the name of Jesus among the nations.
Great salvation. Jesus suffered in stead of His people - this was the lifting up in judgment, on the cross. Christ glorified the Father in suffering for His people and the Father glorified the Son.
Yes, Jesus is The One. In his doubt, John begins to think he must wait for another Jesus. But Jesus answers him: He is doing what the prophecies said, He is bringing blessing; and the wrath of God came, but fell upon Him at Calvary.
Christ's power and compassion. Jesus shows His right hand of power and His compassion for the people.He provides not only for our physical needs, but also for our spiritual needs - eternal life. Because He gave His life, His body, for our salvation.
Legalism or love? Excellent lesson: deeds done in legalistic fashion, to acquire merits, flow not from love. But the heart of Christian religion is love and compassion, expressed in the love of Christ for miserable sinners.