“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)
Our thoughts are often so different from God’s thoughts and our mental capacities are so limited that we can’t understand who God is, who Jesus Christ is and what the meaning and importance of His ministry is. This is not knowledge we can acquire by thinking hard or by studying for decades. It can only be revealed to us by God: “No one knows who the Son is except the Father, or who the Father is except the Son and anyone to whom the Son chooses to reveal him”, Jesus says in Luke 10:22.
The “wise and understanding” who trust in their own knowledge, don’t understand God’s Kingdom. It is those who have no wisdom of their own to whom God reveals these things. Why does He do this? “So that no human being might boast in the presence of God” (1 Corinthians 1:29). For the Lord knows how quickly we attribute our ‘achievements’ to our own efforts!
Being a child of God is not the result of your own morality or intelligence. It is a free gift, received through faith in Jesus Christ. Being a child of God is nothing to be proud of, but a gift to be immensely thankful for!