The believer, now made a child of God, is a rightful heir of promise.
In Galatians 4, the apostle Paul continues on a similar trajectory from chapter three where he put forth that all who believe are made children of God through faith (Gal. 3:26) and heirs according to God’s promise to Abraham (Gal. 3:29).
In chapter three Paul likewise pointed out that the law was like a guardian or schoolmaster—a temporary institution until a child would reach adulthood. Now, in a similar metaphor he concludes that slaves and sons are not all that different until the time of adulthood comes.
Even in the modern world we can see the truth of this. Children under 18 in America are subjected to their parents’ authority. While they are free beings by nature, they have limited freedom because of their age.
Paul uses this metaphor in this context not regarding our own awaiting of maturity, but instead the awaited maturity of history itself.
“But when the fullness of time had come, God sent forth his Son” (Gal. 4:4a).
This time was long awaited.
From Genesis 3 we knew the offspring of the woman would crush the head of the serpent. From Genesis 22 we knew that in Abraham’s offspring all the nations of the earth would be blessed. From Micah 5 we knew that He would be born in Bethlehem. From Isaiah 53 we knew that He would be a suffering servant. From Daniel 7 we knew that He would be like a Son of Man and certainly this list is of expectations is not exhaustive.
Some of these promises were over 1,000 years old. Some were centuries old. Yet, they all awaited this specific moment when the eternal Word of God became flesh and dwelt among us (John 1:14). A time that was perfectly set in the sovereign plan of God.
Beyond the prophetic side of things, there is also an entire historical background study that is super fascinating concerning the timing of Christ’s coming.
If you look at the conquests of Alexander the Great and the Hellenization of the known world, followed later by the conquest of the Romans, the stage was perfectly set. There was a fairly universal language in much of the empire, Koine Greek, and the peace of Rome offered an opportunity for the gospel to travel to faraway lands in short order. It was the “fullness of time.”
Jesus came at just the right time, and He came for a purpose:
“But when the fullness of time had come, God sent forth his Son, born of woman, born under the law, 5 to redeem those who were under the law, so that we might receive adoption as sons” (Gal. 4:4-5, emphasis added).
Christ came into this world, born as the rest of us and born under the law. However, He perfectly kept the law of Moses—all 613 commandments without a single fault. He was completely without sin (2 Cor. 5:21; Heb. 4:15; 1 John 3:5).
As such, He had the perfect credentials as the “Lamb of God” without any spot or blemish, and He became the once-and-for-all-time sacrifice for our sins to redeem us from the law and its bondage. Because of this, we are not saved by our keeping of the law, but by Jesus’ keeping of it and our faith in Him!
The Son came into this world to liberate us from our slavery and in Jesus Christ we are not only no longer slaves—we are sons.
“So you are no longer a slave, but a son, and if a son, then an heir through God” (Gal. 4:7).
We can address the Creator of the universe as “Abba” or “Dear Father” and it is all because of grace.
Let us never take our adoption into the family of God for granted.