It is still His, and, moreover, it is only to be found "in Him." "Surely shall one say, In the Lord have I righteousness," and "In the Lord shall all the seed of Israel be justified, and shall glory" (Isa. 45:24, 25). "We are made the righteousness of God," but only "in Him" (2 Cor. 5:21); and if we would have "the righteousness which is of God by faith," we "must win Christ, and be found in Him" (Phil. 3:9); for this righteousness is part of that "fulness which dwells in Him" (Col. 1:19), and which is "treasured up for us in Him."
The whole merit is His –
the gracious imputation of it only is ours.
Christ fulfilled the law of God in perfect obedience in His earthly life; He perfectly fulfilled its penalty in His death on the cross; He fully satisfied God’s holiness, justice and wrath in His once for all propitiatory sacrifice on the cross and in resurrection secured for us our justification.
Therefore, sinful man may have peace with God by grace through faith in Jesus Christ the Lord by being justified by His blood (Roms. 5:9); and that His righteousness, by virtue of His sinless life lived and His atoning death, is now imputed to us by faith (2 Cor. 5:21) so that we are no longer under the curse of the Law; the demands of the Law; or under the justice and wrath of God. But we are clothed with the perfect righteousness of Christ, being regenerated and sealed by His Holy Spirit (Eph. 1:13-14).
It is as the Apostle Paul so wonderfully states:
“He saved us, not on the basis of deeds which we have done in righteousness, but according to His mercy, by the washing of regeneration and renewing by the Holy Spirit, whom He poured out upon us richly through Jesus Christ our Savior, so that being justified by His grace we would be made heirs according to the hope of eternal life." -Titus 3:5-7