Why did Jesus have to die for things I did? How is that fair?

If Christianity meant that God punished an unrelated innocent person instead of the guilty, the fairness objection would be powerful.

But that is not quite the Christian claim.

Christianity says that God was acting in Christ to reconcile the world to himself, and that Jesus gave his life willingly. The cross is therefore presented as God's self-giving action, not a third party being dragged into someone else's punishment.

Why was any costly reconciliation necessary? Because forgiveness does not make wrongdoing costless. When serious harm is forgiven, somebody absorbs a cost rather than pretending the harm never happened.

Even that analogy is incomplete. The New Testament describes the cross in several ways: sacrifice, substitution, reconciliation, victory over evil, forgiveness and rescue.

Christians disagree about how those images fit together. What they share is that Jesus is not an accidental victim paying a bill God arbitrarily assigned to him.