Romans 8:3, For God has done what the law, weakened by the flesh, could not do. By sending His own Son in the likeness of sinful flesh and for sin, He condemned sin in the flesh.
The law cannot save; only faith can save. The flesh is too weak to keep the law—our will is too weak. This is why faith is necessary, for it takes hold of what the will cannot grasp. It is necessary to keep and fulfil the law in order to earn a right status with God. But no one can do this. This is why God sent His Son—fully God and fully human—to do what we are too weak to do. As God, only He could fulfil the law; as a human, He subjected Himself to death under the law.
Many unbelievers exclaim, “How could God do that to His own Son!” Exactly. That’s the point. How could He do that? Imagine the anguish to see His only Son die! He did what He would not allow Abraham to do with his only son Isaac (Genesis 22). They make this exclamation to make God the villain and thus devalue the death of Christ. They assume Jesus was forced—that He had no choice. But He did have a choice; His choice was to die for you and me. Speaking on Christ’s humility, Paul wrote, “And being found in human form, He humbled Himself by becoming obedient to the point of death, even death on a cross” (Philippians 2:8). Christ chose to step down from His heavenly throne and to take on our weak, disgusting flesh to die for you and me.
His death cleared our guilt under the law. If this makes you feel guilty, good. You should. You and I put Him on the cross. But He has transferred His righteousness to us, making us right with God.
If Thy beloved Son, O God,
Had not to earth descended
And in our mortal flesh and blood
Had not sin’s power ended,
Then this poor, wretched soul of mine
In hell eternally would pine
Because of its transgression.
But now I find sweet peace and rest,
Despair no more reigns o’er me;
No more am I by sin opprest,
For Christ has born sin for me.
Upon the cross for me He died
That, reconciled, I might abide
With Thee, my God, forever.
I trust in Him with all my heart;
Now all my sorrow ceases;
His words abiding peace impart,
His blood from guilt releases.
Free grace through Him I now obtain;
He washes me from every stain,
And pure I stand before Him.
All righteousness by works is vain,
The Law brings condemnation;
True righteousness by faith I gain,
Christ’s work is my salvation.
His death, that perfect sacrifice,
Has paid the all-sufficient price;
In Him my hope is anchored.
My guilt, O Father, Thou hast laid
On Christ, Thy Son, my Saviour.
Lord Jesus, Thou my debt hast paid
And gained for me God’s favour.
O Holy Ghost, Thou Fount of grace,
The good in me to Thee I trace;
In faith do Thou preserve me.
~LSB #568, Johann Heermann, 1630