The historical fact of the Hellenism of the Jews cannot be doubted. F.F. Bruce states, “Greek would be also used in the Hellenistic synagogues of Palestine, such as the Jerusalem synagogue of the Freedmen of Cyrene, Alexandria, Cilicia and Asia where Stephen debated with his opponents (Acts 6:9); indeed the fact the Greek was the language of these synagogues may have been a principal reason for their members being designated Hellenists.” Here we know that the Greek language played a primary part of the common manner in which Jews communicated in the Dispersion. Bruce continues, “This division between Hebrews and Hellenists was primarily linguistic and cultural, but probably it had theological implications too. The Hebrews were evidently Jews who habitually spoke Aramaic, whose homeland was Palestine (or any other area where Aramaic-speaking Jews lived). The Hellenists, on the other hand, were Jews who spoke Greek and whose way of life, in the eyes of stricter Palestinians, smacked too much of Greek customs. Many of them would belong to the Greek-speaking Diaspora, even if they resided in Palestine for longer or shorter periods; but Palestine had its native Greek-speaking Jews.” There is even a distinction made in the Mishnah (Gittin 9:6, 8) which shows the difference between the Aramaic speaking Jews and the Hellenistic Jews who spoke Greek. Stephen himself belonged to a Hellenistic synagogue in Jerusalem called the synagogue of the Freeman. Its membership embraced Jews from Cyrene, Alexandria, Cilicia, and Asia (cf. Acts 6:9).
Language had an immediate impact on the manner in which the New Testament was written and how the Gospel would be introduced to the nations. This is obvious. Would the New Testament writers, like Paul and Peter, who were sent to the Gentiles, (Acts 13:47, “
"For so the Lord has commanded us: 'I have set you as a light to the Gentiles, That you should be for salvation to the ends of the earth.' "), write in Hebrew for their audience? Or would they send the Gentiles letters written in Hebrew – a language they would have never understood in Hellenized Rome? We know there were four primary languages used in Palestine in the first century: Latin, Greek, Aramaic, and Hebrew. Latin was the scholar’s language at that time and was spoken little. Hebrew was spoken in some synagogues, those who had not been influenced by Hellenization. Aramaic was spoken in certain provinces in the Roman empire, but Koine Greek was the predominate language. If you went to the grocery store, Greek was the language of choice. Stambaugh and Balch bring out an interesting note by the use of coins in those days, “The situation for Greek may be typified by the coins struck by rulers. The Hasmonaeans used exclusively Hebrew until Alexander Jannaeus, who began to use bilingual (Hebrew and Greek) coins in addition. His grandson was the first Jew to issue coins with only a Greek identification. The Herodian princes and Roman procurators also issued only Greek coins.” Greek is also confirmed as the language of common use by Jews in the letters and inscriptions of the day. A letter written by Bar Kokhba himself reads, "Now this has been written in Greek because a desire has not been found to write in Hebrew."
From Jerusalem there is the famous first-century synagogue inscription of Theodotus, a priest and archisynagogos who built the synagogue and a guest house for visitors from abroad and supplied them with water. There are many ossuary inscriptions from Palestine, two thirds in Greek alone, one tenth in Greek and Hebrew (or Aramaic)." Since sepulchral inscriptions probably best indicate the language of the common people, it is significant that the vast majority of those published are in Greek. Books were written in Greek by persons from various social strata and religious parties in the two centuries [b.c.]: 1 Maccabees, Tobit, the additions to Esther, and the additions to Daniel. Many scholars today conclude that Greek was widely used in first-century Palestine by Christians as well as other Jews. I find it especially interesting that most of the burial chambers and sepulchers of the first century Christian Jew were written in Greek and not Aramaic or Hebrew. Stambaugh and Balch also point out that there is a current debate according to the measure of Aramaic and Greek spoken in Palestine in the first century. However, for our purposes it is important to note that scholars conclude “the evidence for He­brew in the century in which Jesus lived is sparse.” This is exceedingly important when dealing with the questions of New Testament Greek MSS.
The Roman church is a good example of what has been said so far. Even by 54 A.D., 20 years after the death of Christ, if Paul had arrived in Rome, as he desired, he would have found a large Jewish population, with groups of Christians coexisting either within the synagogues or as separate house churches. As we know, he came to Rome as a prisoner, escorted by a centurion, but while in Rome he was permit­ted to rent his own lodgings and to circulate freely (Acts 28:30-31). At this point, the Christians seem to have been mostly of eastern origin. They spoke Greek, the language in which Paul had written to them, and they derived their instruction, inspiration, and leader­ship from easterners. For all its diversity, the church in Rome up until the first half of the second century A.D. continued to be a Hellenistic community, speaking Greek and maintaining close contact with the Christian churches in the east. The evidence indicates that some upper-class Romans began to be attracted to Christianity in the first half of the century, but it seems likely that their education and cultural taste made them feel at home in the Hellenistic environment of the church in Rome. It is only around the middle of the second century that we can document any significant conversions among lower-class Romans, who did not speak Greek and would need a translation of the New Testament into Latin. (Bruce, F.F.,
New Testament History, Doubleday Dell Publishing Group, Inc., New York, New York: 1971. p. 161-64)
http://www.apuritansmind.com/Apologetics/McMahonNTWrittenGreek.htm
So it may well seem that Greek was indeed the language of the New Testament writters and that the New Testament may well have been written entirely in the Greek. But hey, I'm not here to knock your beliefs, just wanted to share my own.
God Bless
Till all are one.