The real question is when any of us understood this,,Is it that Jesus saved us on the cross or were we saved at some point from our birth until now? Should we credit our salvation to the cross or at some point in our lives when we said we were?
Notice what the Apostles said in early Acts about the cross, before Paul was called to preach the Gospel of Grace. Jesus’s death and resurrection were used by Peter, not to illustrate the divine exchange as Paul did, but as the final proof that Jesus is indeed the Son of God, the promised Messiah. In fact, not only did Peter not preach the divine exchange aspect of Jesus’s crucifixion on the cross, I notice one constant theme he hammered to his Jewish listeners was that they were responsible for crucifying Jesus.
Acts 2:36, where Peter says, "... Jesus,
whom ye crucified ...." Peter also says in Acts 3:14-15, "But ye denied the Holy One ... and
killed the Prince of life ...." Then in Acts 5:30 he says, "... Jesus, whom ye slew and hanged on a tree." Finally Stephen, who also preached Peter's gospel, told the Jews in Acts 7:52, "Which of the prophets have not your fathers persecuted? and they have slain them which shewed before of the coming of the Just One; of whom y
e have been now the betrayers and murderers ...."
My point is that, until the conversion of Saul/Paul, the crucifixion had been pointed out by the 12 apostles to their intended audience, the Jews, as something to be ashamed of and repented of.
Only after the ascended Jesus revealed the mystery of the gospel of grace to Paul (Ephesians 3:3-5), then all of us Gentile Christians, together with Paul, can look back to the crucifixion and cry: "He loved me and gave Himself for me!" Jesus was not murdered, instead he laid down his life for ME.
Indeed, the follow non-exhaustive list of verses written by Paul that testified to the importance of the cross in the divine exchange is as follows
Romans 3:25 (NLT) For God presented Jesus as the sacrifice for sin. People are made right with God when they believe that Jesus sacrificed his life, shedding his blood. This sacrifice shows that God was being fair when he held back and did not punish those who sinned in times past
1 Corinthians 1:18 New Living Translation (NLT) 18 The message of the cross is foolish to those who are headed for destruction! But we who are being saved know it is the very power of God.
Galatians 6:4 New Living Translation (NLT) As for me, may I never boast about anything except the cross of our Lord Jesus Christ.
Colossians 1:20 (NASB) and through Him to reconcile all things to Himself, having made peace through the blood of His cross; through Him, I say, whether things on earth or things in heaven.
Colossians 2:14 (NIRV) He wiped out the written Law with its rules. The Law was against us. It opposed us. He took it away and nailed it to the cross.
Hebrews 12:2 fixing our eyes on Jesus, the author and perfecter of faith, who for the joy set before Him endured the cross, despising the shame, and has sat down at the right hand of the throne of God.