People will spend their entire lives studying and still not understand who Jesus is. Others will be confronted with him, and in an instant, understand enough to receive eternal life.
Also, once saved, some will spend their entire lives studying, and will still not fully understand who Jesus is. Many will spend much less time, and will have many different ideas of who Jesus is.
We will have debates over what Jesus meant, what Jesus did. We could all agree to live our lives as Jesus would, without agreeing on what that means. The answer to the question “What Would Jesus Do” is debated by scholars and laymen alike.
My point is that I do not have to understand that Jesus was from the foundation of the world, that there is a Trinity, or any number of other important theological points, in order to be saved. John 3:16 says that “For God loved the world so much that he gave his one and only Son, so that everyone who believes in him will not perish but have eternal life.”
Paul expounds in Romans 9:10 “That if you confess with your mouth, “Jesus is Lord,” and believe in your heart that God raised him from the dead, you will be saved.”
Do you need to know the origins of Jesus to confess him as Lord? Do you need to understand the Trinity, or the eternal plan, or even the virgin birth, to believe God raised Jesus from the dead?
I am loath to impose any requirements on people than what the Bible clearly specifies. Would I be comfortable with leaving a person in ignorance of the details of the faith? No. But that’s a different question than whether a person could be saved based on their current knowledge.
Interpreting scripture is one thing, adding whole new books is quite another. That is evidence to me that the Holy Spirit is not at work in the Mormon Church.
“Do you need to know the origins of Jesus to confess him as Lord? “
You need to know enough about Jesus to make a commitment. If you don’t know Jesus from Adam’s housecat and you “confess Him as Lord”, you have not confessed him. You don’t want to confess Jesus only to find you think he was your lawn guy.
That’s why deathbed conversions are so tricky. The person may not know what they are confessing.