He committed no sin, neither was deceit found in his mouth. When he was reviled, he did not revile in return; when he suffered, he did not threaten, but continued entrusting himself to him who judges justly. He himself bore our sins in his body on the tree, that we might die to sin and live to righteousness. By his wounds you have been healed. For you were straying like sheep, but have now returned to the Shepherd and Overseer of your souls.
I Peter 2:22-25
To be honest, I don't fully understand the weight of my sin. My generation makes "atonement" for our wrongs by saying "Sorry" or maybe "Please forgive me if I hurt you." We don't really comprehend the cost of our individual sins or the connection between those sins and death. For God's people who lived under the Old Testament sacrificial system the cost of sin was very personal. Today we often discuss this Old Testament practice with confused looks on our faces, even sometimes putting it down, but it really was a brilliant way for God to teach His people about sin and atonement.
When an Old Testament Israelite sinned he couldn't just throw a half-hearted "sorry" out to God. He went out into his field and found a young animal without defect or blemish, and he took it to the temple. There he symbolically laid his hand on the animals head most likely as a sign of the transfer of his sin to the animal. Then he killed the animal with his own hands before it was burnt as an offering to the Lord to make atonement for his sin. Imagine how real the cost of sin was to him in that moment. He had looked the animal in the eye, laid his hand on its head, and killed the animal- probably by slitting its throat- with his own hand. All of this was a God-given object lesson in the seriousness of his sin. Praise God for patiently teaching His people!
I'm not saying I want to go back to this system of atonement. The truth is that the blood of animals can't atone for sin anyway. (Hebrews 10:4) The whole system was a sign, pointing out the penalty for sin and pointing forward to Christ who is the true "lamb of God who came to take away the sin of the world." (John 1:29) What we have in Christ far exceeds what they had. Yet because we did not see Christ's death, it is all too easy for us to look at our sin cheaply. We are tempted to view Christ's sacrifice on the cross as universal at the expense of it being personal. In fact, it was both. Christ wasn't only the lamb who came to take away the sin of the world, but He was also the one who "bore our sins in his body on the tree." (I Peter 2:24) He bore your sin. He bore MY sin on that tree. The fact that Christ, though perfect, died to make atonement for our sins is a concept theologians call substitutionary or vicarious atonement. In other words, He took your place. He paid your penalty. His blood was applied to the dust of this earth. The very dust from which man was made, to which we will return and that also bears with us the marks of our sin from the Fall. (Romans 8:19-23)
This all has very practical import for how we live now. We dare not look at God's forgiveness as being cheaply attained. We dare not take our sin so lightly as to throw half-hearted apologies at God in our nightly prayers. Rather, we should repent of our sin with tears and mourning knowing the true cost of our atonement. That is not to say that we should fear somehow failing to atone for our own sins. We know that Christ alone has purchased our forgiveness, so we repent with confidence that we are forgiven by the blood of Christ. But knowing how precious that blood is ought to drive us to repentance that includes truly hating our sin.
One thing more. In a spiritual sense (but a very real sense nonetheless) because Christ died as our representative, you and I died to sin on that tree. Therefore, as I Peter 2:24 says we ought to truly die to sin and live for righteousness. Romans 6:1-14 says in part:
"How can we who died to sin still live in it?... We know that our old self was crucified with him in order that the body of sin might be brought to nothing, so that we would no longer be enslaved to sin. For one who has died has been set free from sin....So you also must consider yourselves dead to sin and alive to God in Christ Jesus."