The question is one of reliability. the ability to trace a now existing document to its source, with nearly pinpoint accuracy is more than good evidence.
Tracing something back is not necessarily a test of anything but accurate copying.
We can trace the writings of Shakespeare back with pinpoint accuracy, but that doesn't make it something other than fiction...
Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.
Belief gets in the way of learning--Robert A. Heinlein
How can I possibly put a new idea into your heads, if I do not first remove your delusions?--Robert A. Heinlein
It's not what we don't know that hurts, it's what we know that ain't so--Will Rogers