While working on a bible study on Isaiah 40:8, I noticed that in the New Testament, when Peter quotes this text (1 Peter 1:25), there was an interesting change that is not found in the Hebrew nor Greek versions of Isaiah. Here are the texts for comparison accompanied by English versions:

יָבֵ֥שׁ חָצִ֖יר נָ֣בֵֽל צִ֑יץ וּדְבַר־אֱלֹהֵ֖ינוּ יָק֥וּם לְעֹולָֽם׃ ס

Isaiah 40:8 (MT from the WLC)

εξηράνθη ο χόρτος άνθος εξέπεσεν το δε ρήμα του θεού ημών μένει εις τον αιώνα

Isaiah 40:8 (LXX from the ABP)

The grass withers, the flower fades,
    but the word of our God will stand forever.

Isaiah 40:8 (ESV)

ἐξηράνθη ὁ χόρτος, καὶ τὸ ἄνθος ἐξέπεσεν· τὸ δὲ ῥῆμα Κυρίου μένει εἰς τὸν αἰῶνα.

1 Peter 1:24-25 (Wescott & Hort, abridged)

The grass withers,
   and the flower falls,
   but the word of the Lord remains forever.

1 Peter 1:24-25 (ESV, abridged)

While the differences in word order between the Greek texts of Isaiah and 1 Peter don’t change the meaning, there is one word that is different between both texts (marked with boldface above). The text of Isaiah references the “word of our God” (ρήμα του θεού ημών) whereas the quote in 1 Peter exchanges this phrase for the “word of the Lord” (ῥῆμα Κυρίου).

Now, changing the tetragrammaton “YHWH” (יהוה) to “Lord” (κυριος) was a common practice in the Greek texts of the Bible (LXX as well as New Testament references to the Old Testament). However, this is not the case with Isaiah, as the divine name (YHWH) is not used in the original Hebrew text. So what motivated Peter to replace “God” with the “Lord”, when in other Greek translations of the Old Testament, the Greek word for God (θεος) is always used?

Unintentional Change

Here is J. Ramsey Michaels’ take on this verse, from the Word Biblical Commentary:

There is no way to tell whether the substitution of Lord for God of the best LXX is a deliberate editorial change or (like other small deviations) simply of working with different LXX manuscripts, or Peter was influenced by his memory of the Isaiah passage as a whole, in which “Lord” alternates with “God” or “our God” (cf. especially Isa 40:3, where the two stand in parallelism). The construction must be understood both in Isaiah and in 1 Peter as a subjective genitive :the word which the: Lord spoke. In effect, Jesus “the Lord” assumes the place of central importance. Peter’s assumption is that what Isaiah knew as the word of the Lord lives on as the message of Jesus.

J. Ramsey Michaels, Word Biblical Commentary vol. 49: 1 Peter, pp. 78-79

This sheds some light into the whole God/Lord switch. Out of the two possibilities that Michaels speculates, I think the second one is more plausible (Peter being influenced by his memory of the Isaiah passage as a whole), since we currently don’t have any LXX manuscripts with “Lord” in that verse.

Michaels sort of clears out the God/Lord switch (at least as best as he could with the available evidence). But this doesn’t account for the elimination of the first person genitive in the New Testament quote. While both the LXX and NT versions of the text preserve the genitive third person endings in “of… God” (θεού) and “of the Lord” (κυρίου), the NT discards the genitive first person plural “of our God” (ημών) from the quote. In Hebrew, the first person genitive and God are expressed with just one word “of-our-God” (אֱלֹהֵ֖ינוּ) so if he were translating for the Hebrew, then he could have overlooked the full meaning of the word or simply forgotten to include the first person genitive in Greek. This would make sense if his translation wasn’t so similar (in some instances almost verbatim) to the LXX, which shows a clear influence from the LXX over the MT. Still, even if he were quoting from the LXX, Michaels’ alternative seems to be plausible as the other instances of “Lord” in Isaiah 40 do not include the first person genitive “our”.

Intentional Change

If there is a possibility for an intentional editorial change, I would not side with Michaels’ possibility of a variant LXX manuscript due to lack of evidence and lack of motivation for the switch (again, YHWH to Lord is common and warranted, YHWH to God is less common but still recurrent, but God to Lord is very uncommon). So for there to be an intentional editorial change, it probably would have had to be inserted by Peter himself. In order to understand the reasons why, let’s look at the quote with the complete ending of verse 25, for context:

τὸ δὲ ῥῆμα Κυρίου μένει εἰς τὸν αἰῶνα. τοῦτο δέ ἐστιν τὸ ῥῆμα τὸ εὐαγγελισθὲν εἰς ὑμᾶς.

1 Peter 1:25 (Wescott & Hort)

but the word of the Lord remains forever.”
And this word is the good news that was preached to you.

1 Peter 1:25 (ESV)

In his post-quote commentary, Peter equates the Word of God (which in the text of Isaiah may refer to the Law, the promises of God, the will of God, or a combination of all of these) with the ministry of Jesus (the good news) that was being preached by the early Christians.

On this subject, Paul J. Achtemeier proposes in his commentary on 1 Peter that the change from God to Lord is intentional on Peter’s side, to equate Jesus (who is more often than not referred to as Lord in 1 Peter) with the God of the Old Testament.

[…]the substitution of κυρίου, often used for Jesus in this letter, is motivated by the desire to show that already in Isaiah the coming eternal gospel was announced (so v. 25b). Whether the κυρίου is to be understood as the one who speaks the ρημα (“word”) or as its content is difficult to determine. The context in Isa 40:5 argues for the former, and while either understanding would be appropriate for the application in v. 25b, its use there to describe the content of the gospel probably argues for the latter use. Such a decision is supported by the tendency in Christian tradition to identify the message Jesus spoke and the message spoken about Jesus, and while this letter has no explicit citation of a saying of Jesus, it does refer to him in terms of the content of the Christian message.

Paul J. Achtemeier, 1 Peter: a commentary on First Peter

Achtemeier, while also acknowledging that the reasons for Peter’s edits of the Isaiah texts are suppositions, lays down a good case for intentional substitution. My first impression of this argument was that it seemed redundant to try to point to Jesus through a clever word substitution in the quote, when he is already clarifying this in his post-quote commentary. However, as Achtemeier mentions, there is still some insecurity as to whether he is referring to the Lord as the one who speaks the word or as the word itself.

Understanding Lord as the one who speaks the word is more in line with the reading of Isaiah. Yet, reading the end of verse 25 seems to point in the direction of identifying the Lord as the word itself. The identification of the Lord as the Word of God itself is not unique to Peter, and it seems that the early Bible translators understood it to be that way as well (which is why the Greek word λογος is translated in the same way as the word ρημα in most popular translations, a practice that goes back to before Jerome’s Vulgate).

When it comes to determining the place of this “Lord” in relation to the Word, I think the King James Version translators did a wonderful job of trying to capture both meanings.

τὸ δὲ ῥῆμα κυρίου μένει εἰς τὸν αἰῶνα τοῦτο δέ ἐστιν τὸ ῥῆμα τὸ εὐαγγελισθὲν εἰς ὑμᾶς

1 Peter 1:25 (Textus Receptus)

But the word of the Lord endureth for ever. And this is the word which by the gospel is preached unto you.

1 Peter 1:25 (KJV)

Note that I included the Textus Receptus reading to show that the Critical texts and Majority texts are virtually identical in this verse, so the difference in wording in the English language does not stem from differences in the manuscripts.

Whether or not this change of words was intentional or not, what’s clear is that the message of Isaiah 40:8 remained relevant in the eyes of Peter, and his substitution does not take away nor change the meaning of the message.