We are so accustomed to the Bible as is, we can forget that it is made up of distinct documents that were over time compiled and a list was composed of those that the Church believed to be the inspired word of God, the list we refer to an the canon.
Today we celebrate the Saint whom many attribute with first circulating the list of books that make up what we now call the New Testament. St. Athanaius, bishop of Alexandria who passed from this life on May 2 373, in what is called his 39th Festal Letter in 367 included the list of 27 books that we still use today. Pope Damasus then promulgated the same list in 382. And the New Testament as we know it was fixed.
Over the centuries there would continue to be some debates. Luther attempted to remove Hebrews, James, Jude, and Revelation but found few willing to follow him in this modification of the New Testament. To this day some writers and television programs will suggest that there are other books that should have been included. It was the Holy Spirit that guided the early church through a process of prayerful discernment of which of all the writings floating around at the time were the ones truly inspired by God and which contained things which were contrary to the teaching of Jesus.
As we pick up our Bibles and read, let us remember Athanasius I, from Alexandria Egypt.