A.C. Sundberg’s take on the development of the canon in three successive steps:

  1. the rise of the NT writings to the status of Scripture
  2. the conscious groupings of such literature into closed collections (e.g., the four Gospels, and the Epistles of Paul)
  3. the formation of a closed list of authoritative literature

Source: A.C. Sundberg, “Making of the New Testament Canon,” cited by L.M. McDonald in The Biblical Canon.