Catholic Commentary
Do Not Fear Human Reproach: God's Righteousness Endures Forever
7“Listen to me, you who know righteousness, the people in whose heart is my law. Don’t fear the reproach of men, and don’t be dismayed at their insults.8For the moth will eat them up like a garment, and the worm will eat them like wool; but my righteousness will be forever, and my salvation to all generations.”
Isaiah 51:7–8 exhorts the faithful remnant to reject fear of human reproach and mockery, assuring them that their oppressors will disintegrate like fabric consumed by moths and worms. God's covenant righteousness and salvation endure eternally while human power inevitably decays.
Your mockers are moths eating away—temporal and fragile—while your faithfulness to God is the only thing that lasts forever.
Against this decay, the closing bicolon rings with eternal permanence: "my righteousness (צִדְקָתִי, tsidqati) will be forever… my salvation (יְשׁוּעָתִי, yeshu'ati) to all generations." The two terms tsidqah and yeshu'ah are near-synonyms in Deutero-Isaiah, often paired (46:13; 51:5–6). Tsidqah here means not punitive justice but saving fidelity — God acting in accordance with his covenant promises. Yeshu'ah (salvation) carries the same root as the name Yeshua (Jesus), a connection the New Testament authors and Fathers will exploit fully. The salvation that is "to all generations" (לְדוֹר דוֹרִים, ledor dorim) breaks through the immediate historical crisis of the exile and opens onto a universal and eschatological horizon.
Catholic tradition reads these verses at multiple levels simultaneously, which is the genius of the fourfold sense (CCC §115–119).
Literally, the verses address the Jewish exiles in Babylon, suffering the cultural humiliation of a conquered people whose God appeared defeated. The prophet's pastoral genius is to reframe the power dynamic entirely through the lens of divine permanence.
Typologically, the "people with the law in their heart" points forward to the Church, the new covenant community in whom the Holy Spirit writes the law interiorly (cf. 2 Cor 3:3; Jer 31:33). St. Jerome, commenting on this passage, identifies this community explicitly with those who receive Christ: "Hi sunt qui legem Dei in corde portant, non in lapidibus" — "These are they who carry the law of God in the heart, not in stones." For Jerome, the transition from stone tablets to inscribed hearts is the definitive mark of the new covenant community.
St. Thomas Aquinas (Summa Theologiae I-II, q. 106, a. 1) teaches that the New Law is primarily the grace of the Holy Spirit given internally, with external precepts serving only a subordinate role. Isaiah 51:7 is thus a prophetic anticipation of what Thomas calls the lex nova: the law of the Spirit written on the heart.
The Catechism (§1716) cites the Beatitudes — including "Blessed are those who are persecuted for righteousness' sake" (Matt 5:10) — as the very face of Christ's proclamation. Isaiah 51:7–8 stands as the Old Testament foundation of this beatitude: the reproach of man is transient; the righteousness of God is eternal.
Pope Benedict XVI (Spe Salvi, §2) argues that Christian hope does not rest on human constructions or the goodwill of contemporaries, but on the verbum — the Word — that endures forever. Isaiah's "my salvation to all generations" is precisely this: salvation that no human reviling can undo, grounded in the eternal reliability of God himself.
Contemporary Catholics face a specific form of the reproach Isaiah names: cultural marginalization for holding to Church teaching on life, marriage, sexuality, and social justice. The temptation is not usually outright apostasy but a gradual softening — a hesitation to speak, an anxiety about being mocked, a pruning of identity to avoid contempt. Isaiah 51:7–8 speaks directly to this moment. The prophet does not promise that the contempt will disappear or that it is unimportant; he acknowledges it is real and painful (cherpat adam — the reproach of a person, not an abstraction). What he offers instead is a radical reframing of the time horizon. The critics who dismiss Catholic moral teaching, the colleagues who mock sacramental life, the media voices who caricature the faith — they are, in Isaiah's brutal economy, moth-eaten wool. They will not last. The righteousness of God — and those who carry it in their hearts — will. Practically, this passage is an invitation to examine: Am I diluting my witness because of fear of reproach? Have I allowed the short-term judgment of contemporaries to outweigh the eternal judgment of God?
Commentary
Isaiah 51:7 — "Listen to me, you who know righteousness, the people in whose heart is my law; fear not the reproach of man, nor be dismayed at their revilings."
This third "Listen to me" (שִׁמְעוּ אֵלַי, shim'u elay) oracle narrows the audience from the broad coastlands and peoples of v. 4 to a defined community: those who know righteousness (צֶדֶק, tsedeq) — not merely as abstract doctrine but as lived covenant fidelity — and in whose heart the Torah dwells. The phrase "law in the heart" (תּוֹרָתִי בְלִבָּם, torati belibbam) is a deliberately internalized form of the law, anticipating the new covenant language of Jeremiah 31:33. It describes not a people who follow external rules under compulsion, but those in whom divine instruction has become a constitutive part of their identity. This is the people of the Servant: the faithful remnant who have endured the Babylonian exile without abandoning YHWH.
The imperatives "fear not" (אַל-תִּירְאוּ, al-tira'u) and "be not dismayed" (אַל-תֵּחַתּוּ, al-techatu) echo the great Isaianic comfort formula found throughout chapters 40–55 (e.g., 41:10, 43:1, 44:2). The specific objects of fear are named precisely: cherpat adam — the "reproach of man" — and giddupotam — their "revilings" or blasphemies. These are not abstract fears but the public shaming, social marginalization, and mockery that accompany faithfulness to God in a hostile culture. The prophet names the wound: it is deeply personal. Contempt from fellow human beings cuts deeper than physical suffering because it attacks one's sense of worth and belonging.
Isaiah 51:8 — "For the moth will eat them up like a garment, and the worm will eat them like wool; but my righteousness will be forever, and my salvation to all generations."
The antithetical parallelism of v. 8 is structured as a diptych: the mortality of the revilers set against the eternity of divine righteousness. The imagery of moth (עָשׁ, ash) and worm (סָס, sas, a rare term possibly denoting a clothes-moth larva) eating garments and wool is drawn from everyday life in the ancient Near East, where textile wealth was real and perishable. The metaphor is deliberately undignified: those who taunt and mock the faithful will simply disintegrate, not through dramatic judgment but through the quiet, inexorable process of decay. This is a demythologization of human power. No empire, no mockers, no oppressors — however fearsome in the moment — can outlast the righteousness of God.