The Bible is the book of sacred writings of God’s People of the Old and New Testaments.
The People of God of the Old Testament were the Jews, the descendants of Abraham, Isaac and Jacob, whose name was changed by God to Israel (Gen 32:28). These people are also called the Hebrews. They remain forever as God’s chosen people for from them “according to the flesh” Christ, the Son of God, was born (Rom 9:5). This Son of God is Jesus of Nazareth, the Messiah-King of Israel and the Savior of the world (See Mt 1-2, Lk 1-2, Rom 8:3, Gal 4:4, Heb 1-5). The Old Testamental writings of the People of Israel remain forever as the Word of God for all who believe in God and wish to know His divine Truth and to do His divine Will.
The People of God of the New Testament are the Christians—those who believe in Jesus as “the Christ, the Son of the Living God” and who belong to the Church which He has founded upon faith in Himself (See Mt 16:13-20). The People of God of the New Testament also have their holy writings which bear witness to Christ and which are affirmed to be the Word of God.
Thus, the Bible as a book, or a collection of many books, has two main parts. It has the Old Testament writings which prepare the world for the coming of Christ, and, it has the New Testament writings which testify to the fact that Christ has come and has saved the world.