Sorry, your response is in my eyes incoherent.
You refer to the needs of those who would think themselves saved as a secondary issue. You speak of a journey, yet if there is disagreement on how the journey starts there is real dispute. Again, in a Faith that asks us to love our neighbour as ourselves, the fate of billions of our neighbours is NOT secondary. The eternal fate of billions is NOT secondary.
God is One? There are constant disputes concerning the Trinity, with some Christians rejecting the doctrine. Again even the deity of Christ is disputed (oh yes, they would be JW's, but that is beside the point in this discussion. They see themselves as the true Christians) The exact nature of the resurrection is disputed, with some arguing for what is virtually the resuscitation of a corpse, others arguing for a more "spiritual" nature to Christ "rising". Coming again? Have you not heard of those who argue that he has already returned? The Bible the Word of God? Again, no, Christ is declared by some the actual "Word", and the Bible merely the witness to that Living Word. Many Christians argue that the Bible is in fact not inerrant and has no need to be, and would dispute that it being "inspired" infers any such thing. Again, the simple words "Christ died" are open to various understandings regarding the exact nature of the atonement, not to mention the words "The lamb who was slain before the foundation of the world" which throws further disputations into the mix.
So there you are. The disputes remain. Many Christians would dispute with you as to what is fundamental and what is not, as I would. The nature of each dispute is relevant to very fundamental things, and the only thing that is clear is that those who claim that the Bible is clear on fundamentals are wrong.
Salvation is by Grace? Ah! At last. But not unique to Christianity, and in fact seen more clearly by some in other Faiths that are not given to what can only be called Bibliolatry,..i.e. the reliance upon the word as text and a particular interpretation of it rather than the Living Word, the giver of Grace.