To act [humbly] in this way presumes a heart set at peace by Christ, freed from the aggressiveness born of overweening egotism. That same peacefulness, the fruit of grace, makes it possible to preserve our inner trust and persevere in goodness, “though I walk through the valley of the shadow of death” (Ps 23:4) or “a host encamp against me” (Ps 27:3). Standing firm in the Lord, the Rock, we can sing: “In peace I will both lie down and sleep; for you alone, O Lord, make me dwell in safety” (Ps 4:8). Christ, in a word, “is our peace” (Eph 2:14); he came “to guide our feet into the way of peace” (Lk 1:79). As he told Saint Faustina Kowalska, “Mankind will not have peace until it turns with trust to my mercy”. So let us not fall into the temptation of looking for security in success, vain pleasures, possessions, power over others or social status. Jesus says: “My peace I give to you; I do not give it to you as the world gives peace” (Jn 14:27).
Gaudete et Exsultate 121