When the Galatian believers turned away from the gospel of Christ and began following the false teaching of legalism, they had no idea what they were giving up. Paul strains to make the riches available only in Christ as obvious to them as he possibly can in order to convince them to return to the free grace and life of Christ. In this passage, Paul tells a common story to make his point.
Even though an infant heir is born to his father’s estate, and even though he will one day receive the riches available to him, he is completely powerless to lay hold of that inheritance until the day he comes of age and his father grants him his right. And until that day, he has no different access to the estate than the slaves of the household, even the most trusted of the slaves.
In the same way, Paul says, while we were infants we were enslaved to the basic principles of this world. Before Christ came and changed things for the Galatians, not only were they no better than the infant in the estate, they were, in fact, enslaved by the things of this world. Being a slave to anything is language we don’t like to use, but we have to come to terms with it in order to understand the true state of things between the human without Christ and the moral and spiritual structure of this world.
The things of this world enslave us. Enslavement means coercion. It means your passions and brokenness make you do things you “don’t want to do.” It means they build and shape your desires and as such they cause you to do things. Enslavement means less of me and more of my captor. As my flesh and sinful desires do their work, they become my thoughts, emotions, actions and words. My captor runs me and I fade into the shadows. Enslavement means captivity without hope of freedom. The principles of this world without Christ have no intention of holding onto me for a season and then moving on. This is a lifetime project they are on, and unless something happens I will die enslaved to them.
But there is another option to being an infant or a slave in the household: you can be a son. In one of the more powerful twists in the book, Paul writes:
“But when the fullness of time had come, God sent forth his Son, born of woman, born under the law, to redeem those who were under the law, so that we might receive adoption as sons. And because you are sons, God has sent the Spirit of his Son into our hearts, crying, "Abba! Father!" So you are no longer a slave, but a son, and if a son, then an heir through God.” (4:4-8)
An infant doesn’t have the power in themselves to become the heir, so their Father needs to do the work. And that is exactly what God did. In his eternal wisdom, God sent his Son, the second member of the Trinity, into this world to live this life in this flesh, to die this death, and to conquer it all for God’s children. Then he sent the Spirit of his Son, the third member of the Trinity, to reside within us to secure our relationship and inheritance. As a child of God, we call our Creator, Abba.
The work of Christ in this life was to redeem us and give us the adoption as sons. Christ bought back our lives; he paid the price necessary to put us back into right relationship with God. Then, and only then, do we become God’s sons and daughters.
God walked through the orphanage, picked you, paid the price, signed the papers, and took you home. You are a child of God, and the riches of his life and presence are available to you now and for all of eternity.