The New Testament was written in Greek. This seems strange, since most infers that it should be Hebrew or Aramaic. Why Greek? Because the Greek happened something very similar to what happens today with the English language. English is so prevalent today not because it is simple or easier to master than other languages but mainly because of the British Empire.
In this way, Greek was the most spoken language during the years of New Testament composition from 50 to 100 AD. The fact is that many Jews could not even read Hebrew, and this greatly upset the Jewish leaders! Thus, around 300 BC a translation of the Old Testament from Hebrew to the Greek called Septuagint was carried out, and it was completed around 200 BC. Little by little this Greek translation of the Old Testament was widely accepted and even used in many synagogues. It also became a wonderful missionary tool for early Christians, because now the Greeks could read the Word of God in their own language.
So the authors of the New Testament wrote in Greek. However, they did not really use classical Greek or upper class, but a very common and everyday type of Greek. For many years some scholars ridiculed the Greek of the New Testament because many of his words were strange to those who read the writings of the great Greek classical authors such as Plato and Aristotle. But later many records were discovered of the common people, and incredibly they were the same terms used in the New Testament. The teasing stopped.
In this app you will find an interlinear bible that will help you a lot in the study of the word by the original language that was written.