In 2 Corinthians 5:21, Paul says that “God made him who had no sin to be sin for us…” Let’s leave off the rest of the verse for now.
This verse speaks about both Jesus’ life and death.
“Him who had no sin”=Jesus’ life. “To be sin for us”=Jesus’ death.
Here, Paul first explicitly affirms the sinlessness of Jesus. Since sin is the necessary fruit of our sinful natures, I think it is right to say that Jesus did not have a sinful nature. He was human like us (Rom 8:3), but without any inward or outward sin.
His sinless life was crucial for the death he would die. Because he had no sin of his own to die for, he could fully and perfectly bear the sins of the world upon him.
When we read that “God made him” to be sin for us, we shouldn’t imagine Jesus unwillingly going to the cross (as if the Father at some point had to say, “I’m going to make you hang there on that tree and die for them!”).
In fact, Jesus himself states the opposite in John 10:18a: “No one takes it [my life] from me, but I lay it down of my own accord.” It was the Father’s plan to send the Son (John 3:16), and the Son went, becoming obedient even to death on a cross (Phil 2:8).
So the sinless Jesus was made “sin.” This is a crucial acknowledgment for Christians to make, for we hold precious the idea that Jesus bore the penalty for our every iniquity. God treated Jesus as sin, pouring his wrath on his Son for our salvation. Jesus did not pay for our sins in part but in full.
“For us” is key in 2 Cor 5:21. Jesus’ death was substitutionary. The sinless Son died for us–the sinless for the sinful.
Let’s ask the who, what, when, where, and why questions.
What? Became sin for us.
When? 2,000 years ago.
Where? On the cross.
Why? So that “in him we might become the righteousness of God” (2 Cor 5:21b).