“My little children, for whom I labor in birth again until Christ is formed in you” (Galatians 4:19).

While a baby has all of its parts formed at birth, those parts are not fully developed—that comes with time and growth. So it is with becoming a child of God. Spiritual birth is only the beginning of the process of becoming a full-grown Christian. Evidently, this growth had not yet taken place with the Galatians.
 
That’s the analogy the Apostle Paul uses in this letter to the Galatians as he writes to help them deal with the problem of Judaizing teachers and teaches them about growth as a child of God. His deep concern for them will remain until Christ is formed in them and they grow spiritually.
 
For Christ to be formed in us, we must truly invite Him into our hearts and minds so that He influences not only our thinking but also our actions. We must grow to the point that we get over being self-righteous and we rely on Christ, on His instruction, and on His righteousness for our spiritual condition. He must become the center of our lives if He is truly formed in us.

“You search the Scriptures, for in them you think you have eternal life; and these are they which testify of Me” (John 5:39).
 
Early in His ministry, Jesus has this serious discussion with some of the Jews in Jerusalem. He is here making a direct statement about their spiritual activities but yet implying they have failed to get the message.
 
Yes, they search the scriptures (the Old Testament) and depend on that search for gaining an entrance into heaven, but they have not even reached a proper understanding of who He is, even though the scriptures proclaim that He, the Messiah, is coming.
 
The Jews were approaching the scriptures academically without internalizing the meaning of the message. And the implication is that they had failed.
 
The implication for us is that having an academic knowledge of the scriptures is not enough to satisfy God: we must also put the message into our hearts, allowing it to mold us into the kind of caring person God wants His children to be.

“The stone which the builders rejected Has become the chief cornerstone.” (Psalm 118:22).
 
Looking forward to the coming of the Promised One, David prophesies here about Jesus who would come as a solid spiritual Rock for the benefit of all humanity, both those who lived before the cross and those who lived afterward.
 
When Jesus came, the Jews rejected both Him and His message of salvation for all people, both Jews and Gentiles. The rulers and the ordinary Jews were the builders in this figure, and the chief cornerstone, of course, is Jesus Christ.
 
In spite of the Jews’ rejection of Jesus, He came to the earth and fulfilled the mission to which God had commissioned Him: He came as the Savior of all people—that is, the chief cornerstone of Christianity. Both then and now, those who reject Jesus will be rejected by the Father in judgment.