The answer
Its source is the Holy Scripture, with its two testaments, which is God’s revelation of Himself to man. The first is to the Jews through what is known as the Old Testament, followed by a more evident and definitive manifestation to all men in the Person of the Lord Jesus Christ, which is known as the New Testament.
This Divine Revelation was recorded in holy books by holy men who were moved by the Holy Spirit (2 Pet. 1:21).
Holy Scripture is not one book, but is a group of assorted books comprised in one Book, each of these books is called cepher (from the Hebrew word cepher: book).
These books were written by persons of diverse characteristics, environments, and cultures, who lived in different places and times, and under varying social conditions.
Its writing spanned more than 1500 years, the date of its oldest scripture goes back to more than 3500 years. Despite the variety of Its writers and the differences of their conditions across the ages, in the end, it comes out as one big book containing harmonized smaller ones. This indicates that its author is one, Who is God. Its one aim is the salvation of all men, from all nations, tribes, and tongues. It begins with the Book of Genesis, which speaks of the creation of the world, and ends with the Book of Revelation, which deals with the issue of the end of the world and the life of the other world.
His Holiness Pope Tawadros II
Pope Tawadros II, My Faith: A Series of Dialogues on the Creed (Coptic Orthodox Patriarchate, 2014), 12–13.

