“The last chapter of John clearly states that not everything was written down. Thus the faith was passed from person to person by word of mouth”.
AMEN. But you’ll never get the Catholic-haters to admit the obvious.
Not obvious at all....word of mouth leaves open any and all manner of change according to whatever one might want to determine....thus enters “traditions of men”....and generally all manner of false religions and groups. As it has been throughout History.
Best to stay with Gods Word as the ultimate authority and “let” Him teach you what He wants you to know as His Spirit teaches. ..Just as He asks that we do.