In that same hour he [Jesus] rejoiced in the Holy Spirit and said, “I thank you, Father, Lord of heaven and earth, that you have hidden these things from the wise and understanding and revealed them to little children; yes, Father, for such was your gracious will.” (Luke 10:21)
This verse is one of the only two places in the Gospels where Jesus is said to rejoice. The seventy disciples have just returned from their preaching tours and reported their success to Jesus.
Notice that all three members of the Trinity are rejoicing here: Jesus is rejoicing, but it says he is rejoicing in the Holy Spirit. I take that to mean that the Holy Spirit is filling him and moving him to rejoice. Then at the end of the verse it describes the pleasure of God the Father. The NIV translates it, “Yes, Father, for this is what you were pleased to do” — what you rejoiced to do!
Now, what is it that has the whole Trinity rejoicing together in this place? It is the free, electing love of God to hide things from the intellectual elite and to reveal them to babes. “I thank you, Father, Lord of heaven and earth, that you have hidden these things from the wise and understanding and revealed them to little children.”
And what is it that the Father hides from some and reveals to others? Luke 10:22 gives the answer, “No one knows who the Son is except the Father.” So, what God the Father must reveal is the true spiritual identity of the Son.
When the seventy disciples return from their evangelistic mission and give their report to Jesus, he and the Holy Spirit rejoice that God the Father has chosen, according to his own good pleasure — his own rejoicing — to reveal the Son to babes and to hide him from the wise.
The point of this is not that there are only certain classes of people who are chosen by God. The point is that God is free to choose the least likely candidates for his grace.
God contradicts what human merit might dictate. He hides from the self-sufficient wise and reveals to the most helpless and unaccomplished.
When Jesus sees the Father freely enlightening and saving people whose only hope is free grace, he exults in the Holy Spirit and takes pleasure in his Father’s election.
So, when we see this — in fact, when we know that we are among the chosen children — we too join the rejoicing.