You hear about ‘scripture’ all the time, but what is it?
Simply put, scripture is documentation from God. Hopefully you see the problem with that. If we can’t even prove that God exists, then how can we prove something is validly scriptural? We can’t; all we can do is show that it cannot be disproved to be valid scripture. Just like with God, Himself, we can only hope for a reasonable belief.
What do I mean by a ‘reasonable’ belief? That is, a belief which is not contradicted by any ‘fact’. For instance, the belief that the world is flat is not a reasonable belief, since there is ample evidence that the world is NOT flat.
There are several ‘scriptures’ out there; most God-oriented groups have one (or a set). Most known, of course, is the Bible Old and New Testaments. Also the Torah (a subset of the Old Testament), the Koran, the Book of Mormon and several other books from or through Joseph Smith, the New World Translation and many others, Often one group’s scripture contradicts that of another group. How can we evaluate them to see which are really scripture? It can be a challenge.
First and quite importantly is continuity. It is best to have a documented path from where the scripture was received from God all the way down to ‘today’. In police terms, the ‘chain of evidence’. If you cannot show how the ‘paper’ in front of you got there from where God allegedly provided it, then that casts some degree of doubt on the validity of the paper.
Note that I used the term ‘paper’ twice in the sentence above. You say your scripture is ‘oral’, that is, not written down? That casts a lot of doubt on its validity, since showing that it was not changed anywhere in its progression is much, much harder than written scripture, which is often no picnic itself.
The next and perhaps most critical thing to show is internal consistency. Any document which claims both ‘X’ and ‘not X’ is highly suspect. The problem is, all scripture I am familiar with has had humans involved in writing down the revelations from God, and processing the original throughout history. Since humans are incapable of fully understanding God, the concepts from God may have been muted, or colored by societal influences, or provided in a form suitable for human understanding (symbolic or as a parable) rather than bare fact or just have been changed (deliberately or accidentally). This can lead to an apparent contradiction, which requires further research to resolve.
The Bible has been the focus of relentless attempts to show internal discrepancies, and there are indeed places which appear so. As far as I know, nobody has ever proven the Bible to be out and out wrong, and many of the people who have tried have become believers.
The next test of a document is corroboration. If a book was written about, say Ronald Regan, there are still people alive who could attest to the truth contained therein. And a lot of other books to compare it to. Much scripture is from too far in the past for anyone to still be alive to ask, and other written sources tend to be scarce. For the Bible, the writings of Josephus, a Roman historian, are of use.
For older scripture, archeology can be useful. If valid archeological research contradicts scripture, it would be a severe blow to credibility. So far, every find I’ve heard of either supports or does not contradict the Bible. In many cases, recent finds have eliminated claims that a person, place or culture described in the Bible never existed.
These methods can increase or decrease your reliance on the validity of scripture. But what it really comes down to is whether God speaks to you through the scripture.