3 For what the law could not do in that it was weak through the flesh, God did by sending His own Son in the likeness of sinful flesh, on account of sin: He condemned sin in the flesh,
God did by sending His own [unique] Son
What the law cannot do God can do. He can do it without violating His integrity of absolute righteousness. God must always be consistent with His righteousness. In that way He is true to Himself. He did this by sending Jesus to take our hell that we might have His heaven. He took our condemnation personally on the cross.
There is an importance to the word “own” in “His own Son.” Jesus has unique and special relationship to the Father. He was no remote messenger but someone of the Father’s special possession. He belongs to the trinity. As a member of the trinity He is God.
The Father sent His own Son from glory to earth by the incarnation. God gave His very best, His very own Son who existed with Him for eternity past. Emphasis on the greatness of who was sent is of primary importance here. There is significant contrast between His greatness and the weakness of the law.
The Son succeeded in fulfilling God’s demands where the law itself failed. Jesus met all the just demands of the law. He accomplished what the law could not by condemning sin in the flesh of Jesus.
The foundation for sanctification is not found in chapter eight separated from 7:14-25, but in chapters six to eight together. We must take the doctrine of justification as the basis for sanctification.
God gave His very best to save our souls and sanctify our lives.
The Father loved us to the degree of giving His very best for us—His unique Son. His Son existed for eternity in the past with the Father. The Son did what the Law could not do by condemning sin in His human body.