The Use of the LXX in the NT

If we are correct in arguing that the use of the Greek Scriptures in the NT proves that they were regarded as having at least equal authority to the Hebrew Scriptures, then we should expect the theologically probing rejoinder: “So what?” What difference does it make if the NT writers employed the Greek texts rather than the Hebrew? This is a valid question and deserves a reply. First of all, we should establish what would constitute a valid response to the question. A suitable reply would be one that demonstrated that the Greek Jewish Scriptures influenced the NT writers in such a way that their writings were different as a result. In other words, the content of the NT is substantially different than what it would have been if the Greek translations of the Hebrew books and other Greek Scriptures had not existed.

[...]Another citation that demonstrates the theological influence of the OG is Hebrews 1:6. In Hebrews 1 the writer emphasizes the superiority of the Son through a series of quotations from Scripture. The quotation in verse 6 underscores the subordinate position of the angels in comparison to the Son, because the angels worship him. This argument could not have been made from the Hebrew text because the text that Hebrews cites is not even present in our MT. Though the author of Hebrews may have cited a source verbatim (upon which Odes 2:43 also depends), it is at least as likely that the author reinterpreted a text like OG Deuteronomy 32:43 and applied it to Christ. We have examined this passage in some detail in the previous chapter.

McLay, T. (2003). The use of the Septuagint in New Testament research (144,149). Grand Rapids, Mich.: W.B. Eerdmans Pub. Co.