***If you want to believe Mary is the second Eve, please do. Just don’t claim someone said so in the Bible. Last time I checked, +Justin Martyr’s wiritngs are nbot considered inspired, and he is the one who spearheaded the idea about mary being the Second Eve no doubt based on some apocryphal books.***
In a nutshell. Because there were so many sources floating around, the Church used some of them in formulating doctrine; then they decided that the books as a whole were not inspired, although they kept some of the ideas and doctrines associated with them.
That is why we rely on the Church’s Tradition and not just the Canon of Scripture. The Church has the authority, not Luther’s every milkmaid.
Mark, unlike the Western Church, the Church of the East considers scriptures part of the Holy Tradition, and not separate from it. This is a significant difference. Tradition of the Church is, of course, defined as the life of the Church, so scriptures play a role in it, liturgically and otherwise, and while there is a belief in infallibility of the Church as a whole (i.e. that the gates of hell will not overcome it), there is no claim of any inerrency. It is the duty of the Church to make sure the correct faith is transmitted despite errors and variants that may appear.
The mechanism of self-correction is the same one that is used in Judaism. You do things one way because your parents did them that way. And they did it because their parents did it. If you see someone else doing it differently, you are required to speak up and question it because you know it's wrong. How reliable and fool-proof is such a system I don't have to tell you. It's not, of course. yet they and the EO believe it is.
As for doctrine, that was derived pretty much through two theologians, Origen and Tertullian, both of which eventually straued into heresy. Early fathers such as Ignatius actually make a better case for Montanist heresy then orthodoxy. Irenaeus' concept of Mary is troubling, and before him, Clement of Alexandria and Justin Martyr were anything but theological giants, and Clement was anything but a pillar of orthodoxy. Irenaeus still used oral tradition to a large extent over a century after the initial Gospels were written.
The scriptures were no better. They existed in a variety of versions and Christianity pretty much progressed freely and without too many doctrinal or theological restrictions. Copyists were not professionals and undertook to change manuscripts to keep up with doctrinal developments.
While most churches agreed with basic NT books by the end of the 2nd century, the contents of these books were not the same. They came in different lengths as compared to others by the same name, and some were doctrinally divergent as well. In addition to that, the collection of books read in various churches, besides these heterogeneous NT ones, were books that were later deemed "apocryphal" (i.e. Book of Enoch, very popular and wisely read book in early churches), or outright pagan.
The story we know form the Church is of course different, well choreographed and tailored to fit the doctrine. Some prefer it that way. I don't because it doesn't fit the facts.