“Greek scriptures were in wide use during the Second Temple period, because few people could read Hebrew at that time. The text of the Greek Old Testament is quoted more often than the original Hebrew Bible text in the Greek New Testament[10][11] (particularly the Pauline epistles)[12] by the Apostolic Fathers, and later by the Greek Church Fathers. ”
https://en.wikipedia.org/wiki/Septuagint
“300 years before Christ was born, the Hebrew bible, which Christians consider the Old Testament, was translated into Koine Greek. The title of this translation was called the Septuagint. It is this translation that was used by the Paul, the Apostles, and the early church. ”
http://theorthodoxfaith.com/article/the … ly-church/
“Since Greek was the common language of the Roman Empire, the Septuagint was popular among Jews living under Roman rule. Many of the early Christians didn’t know Hebrew, so they naturally embraced this popular Greek translation as well.”
https://overviewbible.com/septuagint/
https://debatingchristianity.com/forum/viewtopic.php?p=1053355#p1053355