Here is an article I posted a long time ago about how the canon is viewed by Orthodox, Protestants and Catholics. If you goal is understanding, it should help. If it is just to piss in someone else’s wheaties, don’t bother.
How We Got the New Testament - 2 1/2 Views (LONG!)
http://www.freerepublic.com/focus/f-religion/2320483/posts
Is the Protestant canon infallibly determined? How do you know? Who acted infallibly in determining it?
My object is not to "piss in your wheaties," but to humbly point out that Luther's notion of the Bible being "the sole rule of faith" for Christians is logically incoherent.
That's no small thing.
Note that in the first post, I provide the Catholic justification for intellectual trust in the canon of Scripture. It is a non-contradictory account.
OK, the Holy Spirit is telling me that the Catholic canon of Scripture is the true canon.
Now what?
And what do you say to a Mormon who believes in the inspiration of the Book of Mormon?