Well, your friend is wrong. But, since you raised the subject, here is a question for you. At the time of the early christians, there were many different books and letters in circulation. Q: Who decided which books should be in the Canon of Scripture ... and ... by what authority did they make that determination?
God did, by his own authority...
Logically, one would think it's up to the body of Christ, the church (and by no stretch of the imagination does that mean the Catholic religion) to determine which is the true canon...
So how many of those who call themselves Christians accept that the Majority Texts, the Masoretic Texts have books in them that do not belong in the Canon...
I would say probably none...
Then, how many of those same Christians would say that the Catholic version of the scriptures have books in them that are not inspired; do not belong in the scriptures??? A great many...
So it's easy...The body of Christ has spoken...