In 4:6 Paul declares, “And because you are sons, God sent forth the Spirit of His Son into our hearts, crying, Abba, Father!” God’s Son is the embodiment of the divine life (1 John 5:12). Hence, the Spirit of God’s Son is the Spirit of life (Rom. 8:2). God gives us His Spirit of life, not because we are law-keepers, but because we are His sons. As law-keepers, we have no right to enjoy God’s Spirit of life. As the sons of God, we have the position with the full right to participate in the Spirit of God, who has the bountiful supply of life. Such a Spirit, the Spirit of the Son of God, is the focus of the blessing of God’s promise to Abraham (3:14).
In verses 4 through 6 the Triune God is producing many sons for the fulfillment of His eternal purpose. God the Father sent forth God the Son to redeem us from the law that we might receive sonship. He also sent forth God the Spirit to impart His life into us that we might become His sons in reality.
Basically sonship is a matter of life. The position and the right depend on the life. In order for us to enjoy God’s sonship, we need the Spirit. Apart from the Spirit, we cannot be born of God to have the divine life. Once we have been born of the Spirit, we need the Spirit in order to grow in life. Without the Spirit, we cannot have the position, right, or privilege of sonship. All the crucial points regarding sonship depend on the Spirit. By the Spirit, we have the divine birth and the divine life. Through the Spirit we grow unto maturity. Because of the Spirit we have the position, right, and privilege of sonship. Thus, without the Spirit sonship is vain, an empty term. But when the Spirit comes, the sonship is made real. We fully realize God’s sonship in life, maturity, position, and right. The Spirit of sonship cannot be replaced by anything. On the contrary, everything, the law in particular, must be replaced by the Spirit of sonship.
Paul’s concept is that the law was a custodian, a warden. Although the law could keep us in ward, it could not give us the life, maturity, position, and right of sonship. The law cannot bestow a position upon a child. It can only serve as a child conductor. The Spirit, in contrast, gives life, maturity, position, and right. Therefore, the law should not replace the Spirit; the Spirit must replace the law.
Since the law could not produce the reality of sonship, you may be wondering why the Spirit was not sent forth earlier. Why did the Spirit not come before the law? The answer is that the promise given to Abraham needed a period of time in order to be fulfilled. Although God is not slow, He waited two thousand years before sending His Son to fulfill the promise. Actually, God did not act quickly even in giving the promise. He did not come in immediately after Adam’s fall to give to Adam the promise He eventually gave to Abraham. Yes, the promise was given in Genesis 3 that the seed of the woman would crush the head of the serpent. However, God waited until man’s cursed and fallen situation had been fully exposed at Babel before He intervened, called out Abraham, and made a promise to him. At Babel, mankind became confounded, confused, and divided, fully exposed as being under the curse. With such a background, no doubt Abraham deeply appreciated God’s promise. Abraham appreciated this promise more than Adam would have appreciated it, had the promise been given to him immediately after the fall. Therefore, the reason for the delay is found on man’s side, not on God’s side.
The principle is the same with respect to the fulfillment of the promise in the coming of Christ. Suppose Christ had come immediately after the promise was given to Abraham. If such had been the case, the fulfillment of the promise would not have been nearly as meaningful. Consider all that happened between the time of Abraham and the birth of the Lord Jesus. During the course of this period of two thousand years, God’s chosen people were fully exposed. On the one hand, the law exposed their corruption and helplessness; on the other hand, the law kept them until the coming of Christ. The law fulfilled a necessary and useful function in keeping the children of Israel for God. The law preserved God’s chosen people even while it was exposing them.
In 4:4 we see that God sent forth His Son when the fullness of the time had come. Christ came at exactly the right time. Earlier would have been too soon, and later would have been too late. Christ came when the time was right. This is illustrated by the picking of ripened fruit from a tree. If the fruit is picked too soon, it will be unripe. But if it is picked too late, it will be overripe. Christ came at the appointed time, at the fullness of time. For this reason, His coming was full of meaning.