This seems like a key question for Christians - maybe The key question; and it lies behind discussions as to the nature of 'The Church' (in which 'The' has several incompatible, meanings).
My thought experiment is to imagine (a situation that must have been, and indeed still be, common) of someone who has never heard of Jesus, the Bible or any church...
Or someone in the spiritually-equivalent (and nowadays mainstream) situation where everything he has heard about Jesus/ the Bible or any particular church Is False - False and indeed deliberately distorted to the point of inversion.
I mean that as of 2022; the standard and most available 'knowledge' concerning God, Jesus and Christianity is designed to lead people Not to salvation - but instead to fear, resentment, nihilism, despair, affiliation with Satan's agenda - and Hell.
(This is very probably worse than the situation of ancient pagans before 30 AD; who had no explicit knowledge of Christ - but it is equivalent in the sense that true knowledge from external sources is all-but unavailable for most people in the world.).
In such circumstances - can a person achieve salvation?
My answer entails taking a step backwards to the nature of God. It would need to be possible for this imaginary Christianly-isolated person - who lives either without knowledge, or with false knowledge of God - to know and understand the nature of God without being told.
Starting from that which is natural and spontaneous and possible to anyone; a person that might become Christian would need to be able to know from his own experience that God was the creator and loved him - and all Men. Know that God was our divine parent/s - and had for His children dwelling in His creation - a perfected parental love.
That, therefore, this God could be trusted in the way a child trusts a loving Mother and/or Father who also makes the world he lives in.
I believe this is a sufficiently simple and natural belief that could be built-in to Men, and then occur to anyone, and be confirmed by direct knowledge.
From this, if Christianity were to be possible to the uninstructed; it would need to be possible for every person to know Jesus 'already' - so that Jesus could be recognized, loved and followed after biological death, when resurrection was offered.
We need already to be able to recognize Jesus... and I have already said we need built-in knowledge of other kinds - and this points at a pre-mortal existence, before we were incarnated into this mortal world.
If pre-mortal life is regarded as real, then there is in principle no difficulty in recognizing and knowing Jesus specifically and personally, when encountered (without being told about it) - because this knowledge could be carried over from pre-mortal life.
An analogy is the instincts found in animals - when the necessary attitudes, motivations, behaviours emerge spontaneously when a suitable situation happens. Men may also have an 'instinct' to recognize Jesus.
Another way of knowing about Jesus without being told is the guidance of the Holy Ghost. We might be 'told', at the right time, who Jesus was - and that this is Him.
Having recognized Jesus, we would then need to decide whether or not to follow him; and that decision would depend on whether we loved and trusted him, and whether we wanted to go where he wanted to lead us: Heaven.
The above sketch shows that I think it is both necessary and plausible that the kind of God Christians believe-in would and could provide what is required such that every individual Man would be able to follow Jesus to salvation.
And that this would not (in principle) depend on any external and valid source of information, or any particular lifestyle, or institution. It could be available to all.
And that Men could be Christian and follow Jesus in any kind of society - including the actually existing world in which nearly all Christian knowledge is deliberately distorted, falsified and indeed inverted.
The alternative would seem to be a God who did not care enough to provide what all His children needed, or who lacked the creative power to provide directly and individually what each of his children needed.
From this much follows; indeed - I would say that all necessary questions can satisfactorily be answered, and guidance derived - given a correct understanding of God's nature.
For me this is The Key - and the Basis for all that follows.
And it is a thing known personally, directly, individually.
(Metaphysical, abstract, theories serve to explain why this Key-Basic knowledge is indeed valid - and to enable the primary insight to be tested against experience and observations.)
