Her response was “What if Paul already knew that what he and others were writing would be scripture? He and Peter called each others writings scripture at points.”
SCRIPTURES. (Etym. Latin scriptural, act of writing.).
Modern Catholic Dictionary
by Fr. John A. Hardon, S.J.
The only way that we know that any writing is “Scripture” – is the Word of God – is precisely because the Catholic Church specifically founded by Christ “to teach all nations” declared certain writings, and no others, to be inspired by God, and teach no error. She gave the world the Sacred Scriptures by defining which books (writings), no more no less, are the Sacred Scriptures.
The books that actually are declared the inspired Word of God were authorized by Pope Damasus at a Council of Rome in 382, confirmed at the Councils of Hippo, 393, Carthage III 397, Carthage IV in 419 and canonised at the Council of Trent (1545-1563) – 46 books in the Old Testament, 27 books in the New Testament – clearly showing the authority of Christ’s Church, and culminating in the defined Canon of Sacred Scriptures at the Council of Trent.