Unless you believe, you will not understand (cf. Is 7:9). The Greek version of the Hebrew Bible, the Septuagint translation produced in Alexandria, gives the above rendering of the words spoken by the prophet Isaiah to King Ahaz. In this way, the issue of the knowledge of truth became central to faith. The Hebrew text, though, reads differently; the prophet says to the king: “If you will not believe, you shall not be established”. Here there is a play on words, based on two forms of the verb ’amÄn: “you will believe” (ta’amÃ®nÃ») and “you shall be established” (tÄ“’ÄmÄ“nÃ»). Terrified by the might of his enemies, the king seeks the security that an alliance with the great Assyrian empire can offer. The prophet tells him instead to trust completely in the solid and steadfast rock which is the God of Israel. Because God is trustworthy, it is reasonable to have faith in him, to stand fast on his word. He is the same God that Isaiah will later call, twice in one verse, the God who is Amen, “the God of truth” (cf. Is 65:16), the enduring foundation of covenant fidelity. It might seem that the Greek version of the Bible, by translating “be established” as “understand”, profoundly altered the meaning of the text by moving away from the biblical notion of trust in God towards a Greek notion of intellectual understanding. Yet this translation, while certainly reflecting a dialogue with Hellenistic culture, is not alien to the underlying spirit of the Hebrew text. The firm foundation that Isaiah promises to the king is indeed grounded in an understanding of God’s activity and the unity which he gives to human life and to the history of his people. The prophet challenges the king, and us, to understand the Lord’s ways, seeing in God’s faithfulness the wise plan which governs the ages. Saint Augustine took up this synthesis of the ideas of “understanding” and “being established” in his Confessions when he spoke of the truth on which one may rely in order to stand fast: “Then I shall be cast and set firm in the mould of your truth”. From the context we know that Augustine was concerned to show that this trustworthy truth of God is, as the Bible makes clear, his own faithful presence throughout history, his ability to hold together times and ages, and to gather into one the scattered strands of our lives.
24. Read in this light, the prophetic text leads to one conclusion: we need knowledge, we need truth, because without these we cannot stand firm, we cannot move forward. Faith without truth does not save, it does not provide a sure footing. It remains a beautiful story, the projection of our deep yearning for happiness, something capable of satisfying us to the extent that we are willing to deceive ourselves. Either that, or it is reduced to a lofty sentiment which brings consolation and cheer, yet remains prey to the vagaries of our spirit and the changing seasons, incapable of sustaining a steady journey through life. If such were faith, King Ahaz would be right not to stake his life and the security of his kingdom on a feeling. But precisely because of its intrinsic link to truth, faith is instead able to offer a new light, superior to the king’s calculations, for it sees further into the distance and takes into account the hand of God, who remains faithful to his covenant and his promises.