Christ has merited righteousness for us, and faith in Christ is that which renders it meet in God's sight the purchased blessing be assigned. Faith unites to Christ, and being united to Him we are possessed of all that is in Christ, so far as is consistent with our capacity of receiving and God's appointment in giving. Having been made one with Christ in spirit, God now considers us as one with Him in law. It hath no efficacy of itself, but as it is the band of our union with Christ. The whole virtue of cleansing proceeds from Christ the object.
Scripture knows no such thing as a justified unbeliever.
There is nothing meritorious about believing, yet it is necessary in order to justification. The righteousness of Christ is not mine until I accept it as the Father's gift. The believing sinner is justified by faith only instrumentally. Eating is the particular act by which he receives and appropriates food. Strictly speaking, he lives by bread alone, not by eating, or the act of masticating.