Greek Orthodox Church

The Greek Orthodox Church (Greek: Ελληνορθόδοξη Εκκλησία, Hellēnorthódoxē Ekklēsía) is the body of several churches[1][2][3] within the larger communion of the Orthodox Church, sharing a common cultural tradition, and whose liturgy is traditionally conducted in Koine Greek,[4] the original language of the New Testament.[5]

Historically, the term Greek Orthodox has also been used to describe all Eastern Orthodox Churches, since "Greek" in "Greek Orthodox" can refer to the Greek heritage of the Byzantine Empire.During eight centuries of Christian history most major intellectual, cultural, and social developments in the Christian church took place within the Empire or in the sphere of its influence, thus most parts of the liturgy, traditions, and practices of the church of Constantinople were adopted by all, and still provide the basic patterns of contemporary Orthodoxy. However, the appellation "Greek" was abandoned by Slavic and other national orthodox churches in connection with their peoples' national awakenings, from as early as the 10th century A.D.  *Wikipedia*

Why was the Bible written in Greek?

• Only the New Testament is written in Greek. The Old Testament is in Hebrew. And the reason for both is that they were the main language spoken in the area they were written in at the time.

• The Old Testament was written almost entirely in Hebrew. However, Hebrew eventually fell out of use for everyday purposes, with the Palestinian Jews speaking Aramaic and the Jews of the diaspora speaking Greek. During the early second century BCE, a Greek translation, known as the Septuagint (or LXX for short), was created for use by the diaspora Jews. However, the Palestinian Jews continued to use the Hebrew Bible.
  The New Testament was originally written in Greek because Alexander compelled the people in the countries he conquered to speak Greek rather than their own language. All Hellenized countries spoke Greek, and anybody wanting to deal with them had to know Greek. It was thus the common language at that time, so many of the early Christians and potential converts spoke Greek. 
• The other reason the Bible was written in Greek was because it was a very precise language with five tenses to enable narrow definitions and the explanation of abstract concepts, especially spiritual and relational, which in other languages such as English just cannot be easily done. (That is one of the reasons for the many translations of the Bible.)

http://wiki.answers.com/Q/Why_was_the_Bible_written_in_Greek