The books of the Bible beginning with Genesis until the end of Malachi reveal how God manifests His commandments and how people live by these covenants or ignore them. These books, called "Old Testament" by Christians, also contain narration of God's wrath on those who constantly forgot their responsibilities and ignored God's commandments. He told them that the time is approaching when he will reject them as they rejected Him, and invite those who believe in His new covenant to inherit His kingdom (Jeremiah 31:31-37).
When God realized that the time had come to establish the last and eternal "testament," He sent His only begotten Son, Jesus Christ, to establish the new covenant, sealed with His blood. The commandments of the New Testament were taught by Jesus Christ, as witnessed and handed down by His apostles.
Thus, the "Old Testament" includes the books recalling the history, revelation and prophecies concerning the old covenants of God, and "New Testament," is comprised of the books, letters and prophetic oracles written concerning God's new covenant through His son Jesus Christ.
The Old Testament can be classified into four groups:
1. Pentateuch: this term means "five containers," referring to the first five books of the Bible: Genesis, Exodus, Leviticus, Numbers and Deuteronomy. Together these books constitute the Law for which the Hebrew word Torah is commonly used. They offer a review of the history of God's dealing with His people, from creation of the world to the death and burial of Moses and his succession by Joshua. These books record the establishment of Israel as the people of God as well as His commandments.
2. Historical Books: this category includes – Joshua, Judges, Ruth, First and Second Samuel, First and Second Kings, Ezra, Nehemiah, Tobit, Judith, Esther, and books of Maccabees. They narrate the history of the people of God, as well as Israel's relationship with God and with her neighboring nations.∗
3. Books of Wisdom: this category includes the books of Job, Psalms, Proverbs, Ecclesiastes, the Song of Songs, Wisdom, and Sirach (Ecclesiasticus). They examine issues related to the lives of the people of God and their salvation.
4. Prophetic Books: this category includes – the books of Isaiah, Jeremiah, Lamentations, Baruch, Ezekiel, Daniel, Hosea, Joel, Amos, Obadiah, Jonah, Micah, Nahum, Habakkuk, Zephaniah, Haggai, Zechariah and Malachi. They contain oracles delivered and written by prophets to whom God had revealed Himself, and who prophesied about future events. These prophetic oracles are about Israel, most of them written hundreds of years before Jesus' birth. They prophesied about His birth, miracles, suffering, crucifixion and resurrection, which were fulfilled in the life, death and resurrection of Jesus Christ, as confirmed by the books of the New Testament.
(excerpt authored by Bp. Vahan Hovanessian)