"The grass withers; the flower fades but the word of our God will stand forever" (Isaiah 40:8), cited to show the entire Mosaic law-code is declared eternally fixed and therefore cannot legitimately be altered or set aside by the New Testament.

The objection equivocates between two senses of 'the word of God': (a) God's overarching revealed purpose, promise, and character as expressed in speech, and (b) every individual time-bound cultic regulation given at one point in Israel's history. Isaiah 40:8 supports (a); the objection needs (b), which the verse does not assert. Context controls the meaning. Verses 6-7 read: 'A voice says, "Cry out!" And I said, "What shall I cry?" All people are grass, their constancy is like the flower of the field. The grass withers, the flower fades, when the breath of the Lord blows upon it; surely the people are grass.' This is the opening of the exilic 'comfort' oracle (Isa 40:1-11) addressed to a demoralized, defeated community whose national and political hopes had just collapsed with the Babylonian conquest — the contrast being drawn is between the transience of human power, nations, and empires (echoed in ANE royal rhetoric where kings boast of enduring dynasties that history then falsifies) and the reliability of God's spoken promise, specifically the preceding promise of comfort, pardon, and restoration announced in vv.1-5 ('Comfort, O comfort my people... her penalty is paid... the glory of the Lord shall be revealed'). Grammatically, 'the word of our God' (deḇar-'ĕlohênu) parallels 'our God' himself — the claim is about the reliability of divine speech/promise as such, not a statement adjudicating the permanent status of specific Levitical ordinances nowhere in view in this passage. Honest textual note: many scholars (following the standard critical division of Isaiah into chs. 1-39 and 40-55/66, associated with a distinct exilic historical setting) treat Isa 40 as addressing sixth-century BC exiles rather than eighth-century BC Judah — a genuine and long-debated authorship/composition question. It does not, however, affect the exegetical point above, which holds on any authorship view: the verse is comfort-oracle language about the reliability of God's redemptive promise, not a ruling on the eternality of Sinai's ceremonial code. The earliest Christian reading of this very verse confirms this construal rather than inventing it: 1 Peter 1:24-25 quotes Isaiah 40:6-8 verbatim and then explicitly identifies 'the word' with 'the good news that was announced to you' — the gospel — showing that from the first generation, Christians read 'the enduring word' as fulfilled in the gospel of Christ, not falsified by the change in covenant administration.

Christian theology affirms Isaiah 40:8 fully and without qualification: God's word — his redemptive purpose, character, and promise — does stand forever, supremely embodied in the eternal Word (Logos) who 'became flesh and lived among us' (John 1:14). 1 Peter's deliberate application of this exact verse to the gospel shows the earliest church understood itself as the fulfillment, not the contradiction, of Isaiah's promise of an enduring divine word.