R.C. Sproul writes:
We must see that the righteousness of Christ that is transferred to us is the righteousness He achieved by living under the Law for thirty-three years without once sinning. Jesus had to live a life of obedience before His death could mean anything. He had to acquire, if you will, merit at the bar of justice. Without His life of sinless obedience, Jesus’ atonement would have had no value at all. We need to see the crucial significance of this truth; we need to see that not only did Jesus die for us, He also lived for us.