This is a very serious question! In the early church these kinds of questions were literally life and death matters. Back then it was a real possibility for a Christian to be put to death for protecting and hiding Scripture! Knowing this, godly believers wanted to know which books they should be prepared to die for. They wanted to know which books are divinely inspired, which books are canonical, that is, the authoritative and final standard for faith and practice. Complicating matters was the fact that from the second to the ninth century, various so-called gospels and letters were in circulation with advocates claiming that they were authoritative. In this life-or-death context, the most important criterion for the recognition of what was canonical was apostolicity. Apostolicity means that the book in question was written by one of the Apostles or by one of his close associates. Apostolicity also places the date of writing in the first century.
Another criterion for canonical status was the edifying impact of the writing on the individual and collective life of the Christian community. The Gospel of Judas does not meet these criteria. The fact that the Gospel of Judas was probably written in the middle of the second century rules out apostolic authorship. The book certainly is not edifying. In this regard there is almost infinite chasm between the edifying books of the New Testament and the Gospel of Judas. Space does not permit an in-depth discussion of the erroneous and heretical contents of this account. At any rate, the early church rejected the book and considered it to be heretical—and rightly so! The Gospel of Judas is not a part of the divinely inspired biblical canon.
Let us remember that with their lives often on the line, in time the church understood that the canon of Scripture was closed with the penning of the last book of the Bible, the Revelation of Jesus Christ. But I do ask myself: do we today have the same attitude toward the Bible that the early church did? If it were a real possibility for you to lose your life for having Scripture in your possession, would you be willing to put your life on the line for owning a Bible?