“A voice of one calling out in the desert, ‘Make ready the road of the Lord! Make his paths straight!’” [For more on the custom of making a road ready by clearing and leveling it, see commentary on Mark 1:3.]. This quotation in Luke, which comes from Isaiah 40:3-5 (and the quotation in Matthew 3:3 and Mark 1:3) is from the Septuagint, the Greek Old Testament. The vast majority of scholars believe that the New Testament was written in Greek, and there are many reasons for that. A primary one is textual.
There are simply no extant manuscripts of the NT in Hebrew, and the manuscripts in Aramaic (Syriac) do not seem to be the autographs from which the Greek texts came. Similarly, however, the Greek of the New Testament is so markedly stylistically different from book to book that it does not seem possible that there is an underlying Aramaic text. Although there are some stylistic differences in Aramaic writings, the Aramaic texts we have today would not have led to the stylistic differences that we see in the different books of the Greek New Testament.
There is research that indicates that Hebrew was spoken in the first century more than was believed in the past, and this has led a few scholars to conclude that the original texts of the New Testament were written in Hebrew or Aramaic. The argument is that the texts were written by Jews for Jews, and thus would have not been written in Greek but in a native Jewish tongue. However, that misses the point. The focus of the New Testament documents was the Christian Church. They were not written in Israel and they were not written exclusively to the Jews.
There were many Jews, especially in the diaspora, who spoke Greek. When Stephen addressed the Jews in Jerusalem in Acts 7 (likely less than ten years after the death of Christ), he was speaking Greek and quoting from the Septuagint version of the Old Testament. Stephen’s dispute had begun with, among others, Jews from Alexandria Egypt, which is where the Septuagint was written (Acts 6:9). When he was brought before the Sanhedrin, he quoted from the Septuagint, not the Hebrew Bible. One way we know that is while the Hebrew Bible says Jacob’s family who went to Egypt was 70 people, the Septuagint text says 75, and Stephen said 75 (Acts 7:14).
By the time much of the NT was written, God had already moved away from the Jews and was ministering to the Gentiles. It was not so much that God wanted to abandon the Jews and minister to the Gentiles, but when He began to include the Gentiles, and wanted His People to do the same, they resisted. Many Jews resisted God’s Messiah (Rom. 10:1-4), but it seems even the majority of the Jews who believed in the Messiah wanted to bring them under the Law, rather than accept that God had a new program of grace for all people and had moved away from “the yoke of bondage.” We know from the New Testament that Paul was continuously persecuted by Christian Jews.
So the claim that the NT was written by Jews for Jews is not correct. In fact, it seems that the only book of the New Testament that was written in Israel was James. Even Peter wrote from Babylon (or Rome). By the time Paul visited Jerusalem the year he was arrested, none of the original apostles were listed as being there (Acts 21:17ff). Although we do not know the reason the original Apostles likely left Jerusalem, they may have left with the persecution of Acts 12, and not come back, perhaps in part because the Christian Jews in Jerusalem were rejecting the revelation of the New Testament.
James, who was leading the church at Jerusalem at that time, was not the Apostle James, but James the brother of Jesus. It is worth noting that James did not believe that his half-brother Jesus was the Messiah until sometime after the resurrection. He did not believe by the Feast of Tabernacles, less than a year before Jesus’ death (John 7:5), and the evidence is that he still did not believe when Jesus was dying on the cross, which is why Jesus told John to take care of Jesus’ mother Mary (John 19:27). It seems that after his resurrection, Jesus appeared to his family and convinced them he was alive, because “his brothers” were with the disciples in Acts 1:14. However, there is no mention of James until Acts 12:17, during the persecution of Herod Agrippa, when the Apostles apparently were forced to leave Jerusalem. Apparently in their absence, James took over as an elder in the church and by Acts 15 seems to be the leader of the congregation in Jerusalem.
As we can see from Acts (and Galatians), the Christian Jews in Jerusalem completely ignored the revelation that Paul got that was codified in the books of Romans, Corinthians, and Galatians (see commentary on Galatians 2:2). The fact that Paul was ministering to Jews and Gentiles living outside of Israel, is good evidence that he would have written in Greek. Similarly, by the time the Four Gospels were written the majority of the Church was centered outside of Israel, and that goes for the writing of Hebrews, Peter, Jude, and the writings of John as well. Thus it makes sense that the original texts were in Greek, and that is also perhaps why many of the New Testament quotations of the Old Testament are from the Septuagint, as we see here in Luke 3:4.