Now I say, as long as the heir is a child, he does not differ at all from a slave although he is owner of everything,Galatians 4:1(NASB)
The Jews proudly relied on their family connection with Abraham and the keeping of the Law for their salvation, but we are not justified by works of the Law but by faith in Christ. It is a gift of God's grace - through faith alone. Salvation is not dependent on national identity, nor is it inherited from parents. Paul had to refute this deep-seated deception and set out to clarify who were Abraham's natural seed and who were his spiritual seed.
His natural seed are all his physical descendants while his spiritual seed are i) believing Jews - his physical descendants and ii) believing Gentiles - his non-physical descendants. Indeed, the ultimate Seed of Abraham was Christ Who was the promised Son through Whom all the families of the earth would be blessed by His sacrificial death and glorious Resurrection.
It is Abraham's spiritual seed (believing Jews and believing Gentiles), not his physical seed that are justified through faith. It is his spiritual descendants who become sons and heirs - through faith in the death, burial, and Resurrection of the Lord Jesus.
As sons of God, we become spiritual heirs of the promise and have been baptised into Christ and clothed in His righteousness. When we were saved by grace through faith, we were positioned in Him and became one with HIM - making us spiritual descendants of Abraham where there is neither Jew nor Greek, slave nor free, male nor female. All who belongs to Christ are Abraham's spiritual descendants and heirs according to promise.
Earlier in his epistle, Paul used a prison warden and a schoolmaster to illustrate that salvation was by faith in Christ and not by works of the Law. In this verse he uses a child-minder to contrast the spiritual immaturity of those trying to be justified under the Law with the spiritual maturity of those who trust in Christ for salvation. The Law is like a child-minder who teaches and trains an immature youngster, but the Law can never make a young pupil into a full-grown man. It can never justify a sinner - it can only identify a sinner's sinful acts.
The one who follows the Law is like a young child who is heir to a great inheritance, but much too young to reap its benefits. However great the legacy may be, until the child comes of age he is no better off that a servant. In the same way, the one who is not enslaved to keeping the Law, but justified by grace through faith in Christ, is the one who has reached the age of maturity and has received the promise - Christ Jesus our Lord Who gives us victory in this life and great reward in heaven.
How foolish and prideful to choose to be enslaved by of works the Law and become like an immature child who is not entrusted with the glorious inheritance that can be our present possession - by faith. May we realise the terrible bondage under which we place ourselves when we insist that right-standing with God can be gained by works of the Law rather that appropriating all that is already ours - by faith in Christ.
Heavenly Father, how easy it is for us to try to justify ourselves in Your sight through works of the Law rather than accepting our salvation as a free gift of Your amazing grace. Keep me low at the Cross and broken before You, for I know that there are no works of the Law that can justify me in Your sight but simply expose a lack of understanding of Your perfect plan of redemption - where Christ became our sacrifice for sin so that by faith in Him alone we might be forgiven of sin and live with You forever. Thank You in Jesus' name, AMEN.