I’ve not read a more powerful statement on the “righteousness of God”.
The righteousness of God is His forgiveness, the radical alteration of the relation between God and man which explains why, though human unrighteousness and ungodliness have brought the world to its present condition and are intolerable to Him, He nevertheless continues to name us His people in order that we may BE His people. The righteousness of God is righteousness from outside—justitia forensis, justitia aliena; for the Judge pronounces His verdict according to the standard of His righteousness only. Unlike any other verdict, His verdict is creative: He pronounces us, His enemies, to be His friends . . . The righteousness of God is therefore the sovereign and regal display of the power of God: it is the miracle of resurrection. The righteousness of God is our standing-place in the air—that is to say, where there is no human possibility of standing—whose foundations are laid by God Himself and supported always by Him only; the place where we are wholly in His hands for favour and disfavour. This is the righteousness of God; and it is a positive relation between God and man (The Epistle to the Romans, 93).