The justice of God requires a payment for sin — a weight that we, in our imperfection, could never carry. We are like those who have built up a massive debt we cannot pay, and the justice of the universe demands a resolution. That is why the purity of Jesus matters. He is the Spotless Lamb, completely untainted by the failure and rebellion that characterizes the human experience. Because He was perfect, He was the only one capable of stepping into our place. When He walked to the cross, He wasn't a victim of circumstances; He was our substitute. He consciously walked into the path of the consequences we earned, taking the "hit" of divine justice so that we could stand free. It is the ultimate act of a protector absorbing the impact so the vulnerable don't have to.
Isaiah 53:4: "Surely he took up our pain and bore our suffering, yet we considered him punished by God, stricken by him, and afflicted."
2 Corinthians 5:21: "God made him who had no sin to be sin for us, so that in him we might become the righteousness of God."
1 Peter 3:18: "For Christ also suffered once for sins, the righteous for the unrighteous, to bring you to God. He was put to death in the body but made alive in the Spirit."