The Old Testament was written by Jewish Prophets inspired by the Holy Spirit. It was accepted as Scripture before Jesus was born and confirmed by Jesus during his time on earth.
The New Testament was written by the Apostles and those who worked closely with them. They were written under the inspiration of the Holy Spirit. They were recognized as inspired right away and were even cited and referred to as Scripture within the NT Scripture. Over the early centuries there were a few debates about certain books, but on a whole the Scriptures were widely accepted by those within the church. Eusebius (ca. 260-340) compiled a list of the 27 books mentioning 5 that were disputed:
ccel.org/ccel/schaff/npnf201.iii.viii.xxv.html Later Athanasius (296-373) writes a complete list:
newadvent.org/fathers/2806039.htm
I think it is clear from all of the Scripture references in the writings in the early centuries summarized in charts such as this (
ntcanon.org/table.shtml) that Scripture was recognized as Scripture long before there was a council. If the Christians in the centuries before any of the councils could use Scripture and know that it was inspired by the Holy Spirit, then why must someone today who believes the same thing about these writings have to accept the authority of the council? I don’t agree with that claim that the author of your link is making. If my church would have a council and decree that the book of Matthew is canonical, and you think it is canonical, does that mean that you have to believe everything that my church believes as well?
This is a good summary I found recently about the development of the NT Canon:
faculty.gordon.edu/hu/bi/ted_hildebrandt/ntesources/ntarticles/gtj-nt/kent-hownt-gtj-67.pdf