Of primary importance in discussing the development of the New Testament canon is determining precisely what constitutes a “canon.” Historically, three primary schools of thought have emerged concerning the definition of the term the “canon.” Theodor Zahn argued that, since many of the foundational books of the New Testament were regarded as authoritative and scriptural by the end of the first century (as seen by their quotation by Christians such as Ignatius of Antioch), the New Testament canon should be understood as established and collected rather early on in the history of the Church, perhaps by the early second century. A second perspective was that of the late great Adolph von Harnack, who took a more fluid view of canon creation. Arguing that while the texts included in the New Testament where written early on in the Christian tradition, they were not regarded as totally authoritative until several decades (or even centuries, depending on the book) later. A third school of thought, as evidenced by A. C. Sundberg, relies heavily upon the rigid definition of “canon” as an authoritative list of scriptural books.  Thus, while early second century Christians such as Ignatius may have viewed certain books as important and useful, Sundberg maintained that the term “canon” cannot be applied to the Christian New Testament until authoritative canonical lists appeared in the fourth century. 
This post is part of an ongoing series outlining the formation of the New Testament canon.