…all have sinned and fall short of the glory of God, and are justified by His grace as a gift, through the redemption that is in Christ Jesus, Whom God put forward as a propitiation by His blood, to be received by faith.  This was to show God’s righteousness, because in His divine forbearance He had passed over former sins.  It was to show His righteousness at the present time, so that He might be just and the justifier of the one who has faith in Jesus. (Rom 3:23-26 ESV)

Tim Keller’s new book Forgive is an excellent, intellectual discussion of God’s forgiveness and how, as recipients of that forgiveness, we can forgive others.

The book includes an extended discussion of the passage above and the question, “How could it be right for God to punish Jesus for our sins”.  God used the crucifixion and death of Jesus to satisfy His Own wrath toward sin – that’s what “propitiation” means – but how could that be right if Jesus wasn’t guilty of sin?  The question has some legitimacy.  It would be a gross injustice if you sent your child to prison for something you did, and the child took no part in.

Here's where an accurate understanding of the Trinity becomes critical.  Wayne Grudem defines the Trinity this way: “God eternally exists as three persons, Father, Son, and Holy Spirit, and each person is fully God, and there is one God”.  There are not three Gods.  There is not one God Who appears in three different forms.  There is one God, Who exists as three Person, all of Whom have the same essence.  That’s hard to understand, but it is both practical and essential. 

If God punished Jesus for our sins, even though Jesus was a third party to the problem – meaning He wasn’t the one harmed by the sins, nor the one Who committed the sins – it would have been unjust.  But Jesus wasn’t an uninvolved third party.  He is God, Who was harmed by the sins, and He became human – representing those who harmed God.  That means that through Jesus – Who is one with God – God Himself absorbed the loss and took the punishment for our debt and our crimes.