The author here takes time to explain the difference between faith and the righteousness that results from having faith in Jesus Christ. This is done chiefly by defining what faith is and what it is not. For example, faith is not righteousness, it is not Christ, nor satisfaction to God. Further, Christ himself as the atonement sacrifice is the one who is presented as the ground of our justification.
This article shows that faith find its rest in the completed work of Christ.