How are we righteous in the sight of God? It is assuredly in the same respect in which Christ was a sinner. For he assumed in a manner our place, that he might be a criminal in our room, and might be dealt with as a sinner, not for his own offenses, but for those of others, inasmuch as he was pure and exempt from every fault, and might endure the punishment that was due to us- not to himself. It is in the same manner, assuredly, that we are now righteous in him- not in respect of our rendering satisfaction to the justice of God by our own works, but because we are judged of in connection with Christ’s righteousness, which we have put on by faith, that it might become ours.
Read this slowly and let it sink in! I came across this quote while preparing for my message on 2 Corinthians 5:18-21 for the Campus Outreach National Conference. Good stuff