Some are of the opinion that, because most of the church (including Israelites) spoke Koine Greek, all the New Testament must have been written in Koine Greek, and later translated into other languages. Others are of the opinion that the New Testament was written in Hebrew and later translated to Greek and other languages. Still others are of the opinion that all the New Testament was written in Aramaic and later translated to Greek and other languages. Aramaic and Hebrew are closely related, probably not as close as British English and American English, but probably more like Portuguese and Spanish. Still others believe most of the books were written in Greek, with a couple being written in Hebrew.
Obviously different books of the New Testament were written to audiences of different ethnic heritages, locations, and languages. We know at least some books were written to people in Rome, Ephesus, Galatia, Corinth, Colossea, and Thessalonica. Most people in the eastern Roman empire spoke Greek, while most people in the western Roman empire spoke Latin. It is believed by some that all Jews spoke both Hebrew and Aramaic, while Samaritans spoke only Hebrew. On the other hand, some believe Jews mostly spoke Aramaic, while others believe Jews mostly spoke Hebrew.
Certainly the majority of Bible scholars and the church of the west believe all (or at least the majority) of the New Testament was written in Greek (http://en.wikipedia.org/wiki/New_Testament). Others believe that the books of the New Testament were originally written in Hebrew (http://www.mashiyach.com/hebrew.htm). Still others believe the books of the New Testament were originally written in Aramaic (http://en.wikipedia.org/wiki/Aramaic_primacy). Others believe it was Aramaic or Hebrew, but certainly not Greek (http://www.hebroots.org/hebrootsarchive/0107/0107h.html). We certainly do not have the original texts of any book of the New Testament to be able to prove any position on this subject.
We have to remember that Israel at the time of Jesus and shortly thereafter was multicultural and many people were multilingual. Greek was the lingua franca, the common language. It was the trade language of the Roman Empire, particularly of the eastern Roman empire. So anyone dealing with others in business (like carpenters) would also have spoken Greek. Latin was the language of the ruling government, particularly in Rome and the western Roman empire. Aramaic was also a language common to the middle east, probably including Israel.
There seems to be dispute between “specialists” as to whether Hebrew was the mother tongue of the Jews, at the time of Christ, particularly in the area of Judea, or whether it was Aramaic. Certainly Hebrew was read and spoken in the Temple and Synagogues. It has been thought that certainly the Jews outside of Israel would have been more familiar with Greek than Hebrew or Aramaic, since the translation of the Old Testament into Greek about 250BC. But anyone who read the Jewish Bible (which contains only the books in what we today call the Old Testament) in the Synagogue would also know Hebrew. Even those who could not read it would hear it read in the Synagogue each week on the Sabbath. Everyone dealing with others in business outside the area of Judea would also have spoken Greek, as it was the lingua franca (trade language) of the day. Others believe that Hebrew was the mother tongue of Jews, with Aramaic being the lingua franca of the middle East, along with Greek for those who were not of mid-east decent.
There are some who believe Hebrew was a dead language used only in the religious realm of life by the time of Jesus. However, the majority of the scrolls from the Qumran scrolls (commonly referred to as the Dead Sea) are in Hebrew, with some 5-10% of the texts are written in Aramaic and Greek (http://orion.mscc.huji.ac.il/resources/FAQ.shtml#language). In fact, the copper scroll is distinctly not religious and yet was in Hebrew (http://www.deadseascrollsfoundation.com/commentary.htm). The commentaries found in the scrolls are said to all in Hebrew, not Aramaic (http://www.hebrew4christians.com/Articles/Jesus_Hebrew/jesus_hebrew.html). In fact, even the texts found in Masada were in Hebrew and not Aramaic (http://www.hebrew4christians.com/Articles/Jesus_Hebrew/jesus_hebrew.html).
While there is dispute as to whether Hebrew or Aramaic was the mother tongue of Jewish people, it is not at all certain that most Jews learned any language other than their own mother tongue. Read what Jospehus had to say, in his Antiquities, book XX, chapter XI, section 2 (http://www.ccel.org/j/josephus/works/ant-20.htm),
“I have also taken a great deal of pains to obtain the learning of the Greeks, and understand the elements of the Greek language, although I have so long accustomed myself to speak our own tongue, that I cannot pronounce Greek with sufficient exactness; for our nation does not encourage those that learn the languages of many nations, and so adorn their discourses with the smoothness of their periods; because they look upon this sort of accomplishment as common, not only to all sorts of free-men, but to as many of the servants as please to learn them. “
We know Jesus spoke Hebrew, as He read and taught in the Synagogue and the Temple (Matthew 4:23; Matthew 9:35; Matthew 12:9; Mark 1:21; Mark 1:39; Mark 6:2; Luke 4:14-21; Luke 6:6; Luke 13:10; John 6:59; John 18:20). Jesus spoke to Saul in Hebrew (Acts 26:14) and Saul learned from Gamaliel (Acts 22:3), so Saul undoubtedly was fluent in Hebrew. Jesus is thought to have spoken Aramaic, as some of the quotes from Him in the Gospels appear to be in Aramaic (Matthew 27:46; Mark 15:34; John 1:42). However whether this was Aramaic or poorly transliterated Hebrew is in question. We also have examples of Jesus speaking to Roman Centurions (Matthew 8:5-13; Luke 7:1-6; Matthew 27:11), most likely in Greek since it was the common language of the eastern Roman Empire (although this is not absolutely certain). We also have the example of Jesus speaking with Pontius Pilate (John 18:28-38), which probably would have been in either Latin or the trade language Greek. Undoubtedly Jesus would have spoken Hebrew, Aramaic, and Greek , and possibly Latin (http://www.abc.net.au/rn/arts/ling/stories/s1066733.htm). We also know the the sign above Jesus was in Hebrew, Greek, and Latin (John 19:18-22, note: only the NIV uses ‘Aramaic’, all other versions seem to use ‘Hebrew’). According Acts 22:2, Paul spoke in Hebrew in the Synagogue (only the NIV uses ‘Aramaic’). In fact, in almost every place the NIV uses ‘Aramaic’ all other versions use ‘Hebrew’.
Many believe that the book of Matthew was written originally in Greek, but this does not match what church fathers said. Matthew was written in Hebrew and translated to Greek, as the Church Fathers wrote.
Papias (60-130 AD) wrote,
“Matthew wrote down the sayings in Hebrew and each translated it as he was able”, (Eusebius, H.E. [the History of the Church], 3.39; cf. 3.24) http://www.ccel.org/ccel/schaff/anf01.vii.ii.vi.html.
“Matthew; it was published for believers of Jewish origin, and was composed in Hebrew letters/language”.
Pantaenus, c.180s, an early church missionary and Bible scholar, travelled to ‘India’ (probably referring to the areas east of the Red Sea, including Arabia, Persia, and Parthia) to preach the gospel but found that the apostle Bartholomew had gone there before and left behind Matthew’s gospel, “in the actual Hebrew characters” (Eusebius, H.E., 5.10; cf. Jerome, De.Vir.Ill. 36) (all the above quotes were taken from http://www.biblicalhebrew.com/nt/hebrewgospel.htm).
Others are of the same opinion (http://www.catholicplanet.com/TSM/NT-Matthew.htm).
In fact, Jerome, who wrote in his Lives of Illustrious Men, chapter 3, was clear even the Bereans used Matthew’s letter in Hebrew:
“Matthew, also called Levi, apostle and aforetimes publican, composed a gospel of Christ at first published in Judea in Hebrew for the sake of those of the circumcision who believed, but this was afterwards translated into Greek though by what author is uncertain. The Hebrew itself has been preserved until the present day in the library at Caesarea which Pamphilus so diligently gathered. I have also had the opportunity of having the volume described to me by the Nazarenes of Beroea, a city of Syria, who use it. In this it is to be noted that wherever the Evangelist, whether on his own account or in the person of our Lord the Saviour quotes the testimony of the Old Testament he does not follow the authority of the translators of the Septuagint but the Hebrew. Wherefore these two forms exist ‘Out of Egypt have I called my son,’ and ‘for he shall be called a Nazarene.’ ” (see Mt 2:15 and 2:23, verses where Matthew quotes Hosea 11:1 and Judges 13:7) (http://www.ccel.org/ccel/schaff/npnf203.v.iii.v.html)
Note that Jerome said the Bereans in Syria at the time still used the Gospel of Matthew written in its original Hebrew. Since they would have known Aramaic, there was no reason for them to describe it as being in Hebrew if it were in Aramaic. Thus, there is no question the Hebrew language was in use, rather than Greek or Aramaic. In fact, Jerome said in Lives of Illustrious Men, chapter 36, that the book of Matthew was taken back to Alexandria:
Pantaenus, a philosopher of the stoic school, according to some old Alexandrian custom, where, from the time of Mark the evangelist the ecclesiastics were always doctors, was of so great prudence and erudition both in scripture and secular literature that, on the request of the legates of that nation, he was sent to India by Demetrius bishop of Alexandria, where he found that Bartholomew, one of the twelve apostles, had preached the advent of the Lord Jesus according to the gospel of Matthew, and on his return to Alexandria he brought this with him written in Hebrew characters. (http://www.ccel.org/ccel/schaff/npnf203.v.iii.xxxviii.html)
The book of Hebrews was thought to be written in Hebrew first and translated to Greek by someone who knew Greek very well (http://www.ccel.org/ccel/schaff/npnf203.v.iii.vii.html).
We know the mindset of the speakers was Hebraic. We know they were deeply influenced by the Hebrew way of thinking and by the Old Testament. It appears the evidence shows Hebrew was not a dead language at the time of Christ after all. But even so, we simply have no original texts of the New Testament. So unfortunately, while I had planned on making some decisive statement on the language of the original text, I find myself unable to do so. There are simply too many questions. But It is safe to say that God is powerful and loving enough to ensure the message He wanted us to have has been maintained through the years. So regardless of whether we might have a fuller understanding of what God said through reading original language texts, we have the message we needed to have to be able to be the men and women God has called us to be. The majority of the text we have is from the Greek translations, although we also have texts from the Aramaic translation that can be used together to ensure we have accurate Bibles.
I DO think it is safe to say that Jesus and the disciples mostly used a Semitic language in every day use, but they would have known three, if not four languages: Hebrew, Aramaic, Greek, and possibly Latin. We have evidence of early church fathers saying at least 2 books being written in Hebrew. Other than that, it is currently next to impossible to state unequivocally which language the New Testament was written in. But while both the Aramaic Primacy and Hebraic Primacy groups make strong points, I find neither of them conclusive. Even so, I lean toward the Hebraic Primacy theory, as it certainly appears to make the most sense. So ultimately, I believe the original books were written in Hebrew, or possibly Aramaic, and later translated into Greek.