The question has more to it than might appear at first. When the 27 different documents that are now collected into what we call “the New Testament” (or what could be called “the Apostolic Writings”), none of the writers knew they were writing for a collection or that they were writing scripture. What was happening in the Yeshua movement that gave birth to these documents? The gospels in particular have an interesting purpose and origin. The generation of eyewitnesses and apostles were passing away. See more and the video “Why the New Testament?” here at the Musings blog.