Reliance on writing instead of memory is dangerous. Texts can be rewritten and were, in fact, rewritten countless times. Also the very existence of a text itself discourages learning. One can always put the book aside, telling himself that he will read it later. That’s why traditional oral preservation of wisdom was so important. Vedas existed for centuries before getting written down. Same with folk tales, bylinas, epics etc, they all were transmitted orally by the professionals. This is also the reason why they existed in poetic form only. Subverting the poem is far more difficult since each word is tied with another and it takes great skill to take something out and substitute it something new. That’s why we can easily tell what parts of are christian contaminations.
Naturally, memory is not perfect either, but again, due to a very strict poetic structure one would rather skip a part or just tell it in prose, rather then inventing something of his own.
Alas, we no longer have great bards of old to share our ancestral tales and even those who attempt to fill their role nowadays rely on texts first, not bothering to learn by heart.
In some cases there’s no texts to begin with. Needless to say, this complicates things. A lot. When you have no reference besides some vague mention by foreign and/or christian scholars (basically the same since christians are mental/spiritual foreigners) revival of the old ways seems impossible. Yet, we persevere. After all, even what little we got can be used well if analyzed properly.
But, here’s another question. What if there’s nothing at all. What if, we don’t even know the names of our native Gods? This will leave us with a very primordial paganism. One where actions speak louder than words, there’s no mystic realms or supernatural, only Nature itself and us. And if this Nature is indeed natural (i.e. not an artificial environment like modern cities) we will inevitable end up developing new myth and creating names. But the core will always be the same. We will have a god of Sky, because there is sky in Nature. We will have a god of Thunder, because there is thunder Nature. That’s why Greeks had Gaia as a progenitor of all Gods. They are in Nature and of her. But we will also eventually add human nature to them, which, again is natural and of nature. We will make our Sky God into a wise, mature leader observing the world from his high throne. We will make our Thunder God into a heroic, young warrior, who strikes as fierce and fast as lightning itself. We will eventually develop smelting and make our Fire God into a stout craftsmen who never leaves his smithy.
Paganism is Natural hence requires nothing but Nature and with it there’s no need in dusty tomes.