“Satisfaction is the act of Christ, God-man, presenting himself as our surety in obedience to God and love to us; to do and to suffer all that the law required of us: thereby freeing us from the wrath and curse due to us for sins.”
1. “It is the act of a God-man; no other was capable of giving satisfaction for an infinite wrong done to God. But by reason of the union of the two natures in his wonderful person, he could do it, and hath done it for us. The human nature did what was necessary in its kind; it gave the matter of the sacrifice: the divine nature stamped the dignity and value upon it, which made it an adequate compensation: so it was the act of God-man; yet so, that each nature retained its own properties, not withstanding their joint influence into the effect. “It was God that redeemed the church with his own blood,” Acts 20:18. If God redeems with his own blood, he redeems as God-man, without any dispute.”
2. “If he satisfy God for us, he must present himself before God, as our surety. In our stead, as well as for our good; else his obedience had signified nothing to us; to this end he was “made under the law” Galatians 4:4, comes under the same obligation with us, and that as a surety, for so he is called, Hebrews 7:22. Indeed his obedience and sufferings could be exacted from him upon no other account. It was not for anything he had done that he became a curse. It was prophesied of him Daniel 9:26 “The Messiah shall be cut off, but not for himself;” and being dead, the scriptures plainly assert it was for our sins, and upon our account: 1 Corinthians 15:3 “Christ died for our sins “According to the scriptures.”
“And indeed, the very consideration is that which supports the doctrine of imputation of our sins to Christ, and the imputation of Christ’s righteousness unto us, Romans 5:19. For how could our sins be laid on him, but as he stood in our stead? Or his righteousness be imputed to us, but as he was our surety, performing it in our place; so that to deny Christ’s sufferings in our stead is to lose the cornerstone of our justification, and overthrow the very pillar which supports our faith, comfort and salvation. Indeed if this had not been, he would have been the righteous Lord, but not the Lord our righteousness, as he is stiled, Jeremiah 33:16. So it was but a vain discretion to say it was for our good, but not in our stead: for had he not been in our stead, we could not have the good of it.” ~ John Flavel
*Works of John Flavel, Volume 1, pages 178-180