The idea that one supposedly must believe and accept belief in one specific set of scriptures stands to no sense, imo. Let me explain.
Moses existed roughly somewhat over 3000 years b.p., and Jesus existed around 2000 years b.p. OTOH, yet we know that humans existed as humans more than 5,000,000 years ago. So for you math whizzes, do the math: 3000/5,000,000 = ? So, didn't God care about those who existed throughout most of human history?
And both Moses and Jesus lived in one small area of the world, so didn't God care about those people who lived in other areas of the world, such as in the Americas for example?
This, and some other things, decades ago led me to believe that God goes well beyond our concept of time and space, thus must be universal in nature.
I'll stop here as of now, but please don't stone the messenger, OK?
God's scriptures are found in all societies. In essence, they all call to follow the light of God and holy leaders appointed by him. If people are unaware of who God is channeling his light through, still, they can try to connect to his light and be guided by the holy spirit of the Guides.
The light of Ahlulbayt and there is always an Ahlulbayt, is always connected to all things.
If you read all holy books, they all call to the chosen masters. This includes the Kybalion The Bible and Quran.
Old holy books if they called those leaders chosen shamans or something else, it doesn't matter. Guidance in unseen journey is always by light of the Guides.
Every society knows about the spiritual realm, light and darkness, and that you need Guides from God to guide you in darkness to light.
If they don't know about Jesus or Mohammad who is the last Nabi, it doesn't matter.
There is always a Guide in each time, that if you pray to God to guide you by, he will you guide by him.