Sproul: Is Everything in the New Testament Canon and Should Anything Else be Canon?

Canon means that it is authoritative in the Christian Church. The Protestant Church has the view that the Canon is a fallible collection of infallible books. The Church has three requirements that must be met before a book is accepted as canon.

1. The Author must be an apostle (This alone knocks off many candidates.)
2. They must have been accepted as authoritative by the early church. 
3. They must be in harmony with the other books.