The rejoicing of Jesus is to be found in the words he spoke to his disciples and in his prayer to the Father. They were spoken in the Spirit, just as his commands in Matthew 28:18-20 (cf. Acts 1:1-2) were done in the Spirit. Jesus’ rejoicing arose out of his hearing that the demons were subject to his disciples (Luke 10:20). The disciples were warned not to rejoice in this thing, probably because it was an occasion for God alone to rejoice in. Rather, the disciples were to rejoice in the fact that their names were written in heaven, i.e. they were citizens of the Kingdom of God. Nevertheless, Jesus rejoiced, taking his pleasure in the news of Satan’s defeat.
Part of Jesus’ rejoicing had to do with his victory over his enemies. During the time of Jesus’ ministry, the wise and prudent (Luke 10:21b) spoke and worked against him. They exalted themselves in that they thought their plans and deeds were unknown to God. They drew near to God with their lips, but not their hearts, and they worshiped him according to the wisdom and tradition of men learned by rote (Isaiah 29:13-16). Jesus rejoiced in that the truth of God was hidden from these who opposed him.
In Luke 10:21 Jesus praised the Father as the “Lord of heaven and of earth” (Luke 10:21). The first time God is praised in connection with his being ruler of heaven and earth is in Genesis 14:19. There, Melchizedek blessed Abraham of “the Most High God, possessor of heaven and earth.” This occurred after his return from warring against the victor of the war against Sodom, that is, Chedorlaomer and the kings with him (Genesis 14:17). It seems that Abraham prayed for victory and vowed to God that he would take none of the spoils of the battle, if the God of heaven and earth would be with him in his effort to free Lot from being taken to Mesopotamia as part of the spoils of war (Genesis 14:22-24).
Before Abraham entered the land that the Lord promised him for a possession, the Lord was the God of heaven only (Genesis 24:7), but after Abraham entered the land, and especially after Abraham had fought in the name of the Lord (Genesis 14:17), the Lord was known as the Lord of heaven AND of earth. This seems to hold true that as long as Israel was in the land and worshiping God (Deuteronomy 10:14; Joshua 2:11; 2Kings 19:15; Isaiah 37:16), God was praised as “the Lord of heaven and of earth.” However, when Israel was not in the land, God was known only as “the Lord of heaven” (Genesis 24:7; 2Chronicles 36:23; Ezra 1:2; 5:12; 6:9, 10; 7:12, 21, 23; Nehemiah 1:4-5; 2:4, 20; Psalm 136:26; Daniel 2:18-19, 27, 44; 5:23).
The time of the Seventy’s return is very much like the return of Abraham after his battle with the kings of Mesopotamia. Jesus greeted the Seventy in the same manner that Melchizedek greeted Abram as he returned from rescuing Lot. It seems that the Seventy’s trust in Jesus is likened to Abraham’s trust in God. As long as there are worshipers of God in the Promised Land, God has a beachhead in the world, and he is Lord of heaven and of earth.
With this in mind, instead of revealing himself to the wise and prudent among the people, God chose to reveal himself to babes—the weak and immature among them, that is, to Jesus’ disciples (Luke 10:21c). This was done in order to shame Jesus enemies, the wise and the powerful among the people, and in order to take away the opportunity of boasting among men (1Corinthians 1:26-29). They exalted themselves against God, whether we are speaking of the Father or Jesus. They took pleasure in their own wisdom, power and discernment, as though, through these abilities, they were able to stand. They rejoiced in their own wisdom and power, while God was left out, except to acknowledge him with their lips and traditions, which they learned by rote.
On the other hand, the disciples of Jesus, the babes in Jesus prayer of praise to the Father, trusted him, and left their businesses etc. to follow him and act upon his wishes. These regarded neither what they possessed nor their own reputations among their families and friends. So, it was these to whom God chose to reveal himself.
Therefore, the favor with God doesn’t rest on knowing how to defend the faith or in knowing about God or about Christ. Rather, God’s favor is seen in the lives of those who know him, and those who know Christ, because, as Jesus claims in Luke 10:22, only the Father knows the Son and only the Son knows the Father. Consequently, if any person actually knows either the Father or the Son, it is because such knowing had been divinely revealed to him. That one is blessed with intimate knowledge of God, acquired only through the power and grace of God, himself, and in this Jesus found reason to rejoice!