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The LXX is not the word of God!
It is a clumsy translation of the ancient Hebrew scriptures, done by Rabbis in the mid second temple period for a handful of Hebrews that lived in Alexandria, and whose birth language was Greek, rather than the Hebrew spoken by the rest of ‘Israel.’
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And yet the NT quotes it 340 times.
The LXX is not the word of God!
The apostles would disagree with you.
I offer the opinion of the King James translators ...
From the original 1611 Preface ...
The translation of the Seventie dissenteth from the Originall in many places, neither doeth it come neere it, for perspicuitie, gratvitie, majestie; yet which of the Apostles did condemne it? Condemne it? Nay, they used it, (as it is apparent, and as Saint Jerome and most learned men doe confesse) which they would not have done, nor by their example of using it, so grace and commend it to the Church, if it had bene unworthy the appellation and name of the word of God.