And therein lies the answer to the question. We're not saved based on what we don't know. It's one thing to be ignorant of some theological truths at the beginning of our discipleship journey. It's quite another to reject the truth once you are presented with it.Salvation is not a theological test. It is a regeneration of a sin sick heart.
Once God quickens the dead sinner and he becomes a living saint, then the Holy Spirit will guide him into all truth.
The genuinely saved person may not understand all the theological points of soteriology but as he grows in grace he will come to accept the Truth and will not deny those fundamental truths.