There is a difference between a formal declaration by the Church (done at Trent) and the establishment of the canon. All the Trent declaration did was formalize the establishment done by earlier Church councils (Hippo I and II) and Pope Athansius (sp??) around 400AD or thereabouts. The Canon wasn't CHANGED, just "recognized officially".
And what Christ holds men accountable to are the teachings of the His CHURCH, as passed on by His Apostles. Scripture is only a part of that teaching. This is why "sola scriptura" is so ridiculous.
As I pointed out to pgyanke, The New Catholic Encyclopedia contradicts your assertion that the Hippo I and II established the canon. Besides those councils were not even ecumenical councils. That The New Catholic Encyclopedia is right when it states that "the canon was not given until rather late in the history of the Church at the Council of Trent" can be seen from from writing of Cardinal Cajetan, probably the leading RC scholar at the time:
"Here we close our commentaries on the historical books of the Old Testament. For the rest (that is, Judith, Tobit, and the books of Maccabees) are counted by St Jerome out of the canonical books, and are placed amongst the Apocrypha, along with Wisdom and Ecclesiasticus, as is plain from the Prologus Galeatus. Nor be thou disturbed, like a raw scholar, if thou shouldest find anywhere, either in the sacred councils or the sacred doctors, these books reckoned as canonical. For the words as well of councils as of doctors are to be reduced to the correction of Jerome. Now, according to his judgment, in the epistle to the bishops Chromatius and Heliodorus, these books (and any other like books in the canon of the bible) are not canonical, that is, not in the nature of a rule for confirming matters of faith. Yet, they may be called canonical, that is, in the nature of a rule for the edification of the faithful, as being received and authorised in the canon of the bible for that purpose. By the help of this distinction thou mayest see thy way clearly through that which Augustine says, and what is written in the provincial council of Carthage."
(In ult. Cap. Esther. Taken from A Disputation on Holy Scripture by William Whitaker (Cambridge: University, 1849), p. 48.)
Cordially,