What is meant here by ‘righteousness?’

Though this word may stand for every virtue which the Christian ought to desire as his meat and drink, we should here especially understand that righteousness of which the book of Daniel speaks: “an everlasting righteousness shall be brought in” (Dan 9:24; see the Study: Daniel’s Prophecy; see Q192, Q235), that is, the justification of guilty man through grace and faith in Jesus Christ.

The Apostle Paul also teaches:

The righteousness of God through faith in Jesus Christ, for all who believe. For there is no distinction: all have sinned and fall short of the glory of God, and are justified freely by his grace, through the redemption which is in Christ Jesus, whom God set forth as a propitiation, through faith, in his blood. (Rom 3:22–25)

The Fathers add that this hunger is never satisfied so as to cease. St Gregory of Nyssa teaches that the soul, ever filled, ever desires more, since God is without limit, and that “never to be satisfied in the desire to see him” is itself the true vision of God (St Gregory of Nyssa, Homilies on the Beatitudes, 4; Life of Moses, II.239). The righteousness received by grace is thus also an unending growth into the likeness of God (see S056).