In this article there will be a discussion on the canonization of the New Testament. With an investigation to find out who was involved in this process. The people and institutions examined will be: Marcion, Irenaeus, Origen, the Synod of Hippo and God. Let us first look at the canonization of the New Testament. The earliest available list of New Testament books is called the Muratorian Canon and dates from around 150 AD. It contains the four Gospels, Acts, 13 letters of Paul, Jude, 2 or 3 letters of John and the revelation of John. These were accepted by the “universal Church”. Some books were left out, they are: first and second Peter, James and Hebrews. However, it is very possible that there was an oversight because Peter was first accepted as a valid book. There is no other book present that accepts the Wisdom of Solomon, this must have been an error because this book belongs to the Apocrypha and it was not added by anyone to the New Testament (Edwards et al, 2009, p. 14) . It is very possible that the first collection of New Testament books by the early church consisted of a collection of Pauline letters. He became very fascinated by Paul's teachings, but he ended up interpreting them in such an unbalanced way that he was considered a heretic. He would compete with the early Christian church by creating his own rival church, which would last for several decades. It would teach that the God of the Old Testament was not the father of Jesus Christ, but rather an evil deity. When he composed his books, he left out the books of the New Testament that were most dependent on Judaism and he also left out the Old Testament. As a reaction against Marcion, such a proposal would make sense. The first canonical “lists” of the New Testament would not appear until about a generation later than Marcion (Varughese, 2004, p..