Not To Be Confused With
“Canon” (the list of Scripture) is unrelated to “cannon” (the weapon). It also differs from “canon law,” which means church regulations.
From Greek kanōn, a “measuring reed” or rule. The canon is the set of books the Church recognized as carrying divine authority. Notably the Church discerned the canon; it did not invent it — and that discernment leaned on the rule of faith and apostolic origin.
Protestant, Catholic, and Orthodox canons differ over the deuterocanon — a fact bound up with the Scripture-and-authority debate.