The Old Testament.
The Bible is customarily divided into two books: The Old Testament and the New Testament. We should note, however, that the word testament is not totally appropriate to designate the character of these two books, but rather the designations New Covenant and Old Covenant. (Some Bibles, such as the Slavonic and Russian, use the designations Old Law and New Law to refer to these two parts.) In any case, the Old Testament may be described as the literary expression of the religious life of ancient Israel.
This literary expression of Israel's religious life extended over a thousand years from the first to the last books of the Old Testament and reflects many facets of the life of Israel, taking many forms: prose and poetry, myth and legend, folk tale and history, sacred hymns and a superb love song, religious and secular laws, proverbs of the wise and oracles of the prophets, epic poems, laments, parables and allegories. Yet, despite these varied forms, a common theme emerges this book is a history of God acting in history, that is, Salvation History, It is a history of a people chosen by God out of whom would come the Messiah, Jesus of Nazareth, the Son of Mary and the Son of God, the Word, the Second Person of the Trinity.
In Jewish tradition, the Scriptures were divided into three parts: The Law (the first five books), the Prophets (Former Prophets: Joshua, Judges, 1st and 2nd Samuel and 1st and 2nd Kings; Latter Prophets: Isaiah, Jeremiah, Ezekiel and the Twelve Minor Prophets), and the Writings (the remainder of the Old Testament books). Later, just before the New Testament era, the Hebrew Scriptures were translated into Greek at Alexandria, Egypt (the so-called Septuagint LXX). This translation included books and portions of books not found in the Hebrew Scriptures (the so-called Apocrypha or Deutero-canonical books). It is this later Greek (LXX) Scripture that is considered the official text for the Orthodox Churches. In any case, the original language of the Old Testament was Ancient Hebrew, although parts were written in Aramaic (a more recent Semitic language).
The New Testament.
More than 500 years before the birth of Christ, the Prophet Jeremiah predicted that the covenant relation of God with His people, instituted on Mt. Sinai, would give place in the future to a more inward and personal one (Jer. 31:31-34). With this in mind, St. Paul regarded the Christian Dispensation as being based on a new covenant, which he contrasted with the old covenant of the books of Moses (2 Cor. 3:6-15). By His sacrificial death, Christ became the mediator of a new covenant (Heb. 9:15-20).
The books of the New Testament, of which there are twenty-seven, fall into four categories: 1) Gospels from Evangelion or Good News, because they tell the Good News of Jesus Christ Sts. Matthew, Mark, Luke and John; 2) Church History The Acts of the Apostles; 3) Epistles (or Letters) of which there are twenty-one, written by Sts. Paul, James, Peter, John and Jude; and 4) an Apocalypse, that is, a Revelation or disclosure of God's will for the future, hence the title: The Revelation to St. John. All of these books were written in the koine or common Greek of the time, which was in common use throughout the Roman Empire at the beginning of the Christian era.