"God counts us as having His righteousness in Christ because we are united to Christ by faith alone. That is, we are counted as perfectly honouring and displaying the glory of God, which is the essence of God's righteousness and which is also a perfect fulfilling of the law. This is what God imputes to us and counts us as having because we are in Christ who perfectly honoured God in His sinless life. It is not nonsense. It is true and precious beyond words".
John Piper - "The Future of Justification - A Response to N T Wright" - IVP, Nottingham (2008) - (p165).