What does it mean that an unsaved person does not understand the Bible?

Question about Spiritual Understanding

So, someone who is “saved” and accepted Jesus as his Savior can understand the lessons taught in the Bible, right? Now, if that same person snaps out of the trance of indoctrination and realizes that it is false and is now a devout atheist, does that mean that he forgets what was taught when he was a believer? 

Scripture:

1 Cor.2:11 For what man knoweth the things of a man, save the spirit of man which is in him? even so the things of God knoweth no man, but the Spirit of God. 12 Now we have received, not the spirit of the world, but the spirit which is of God; that we might know the things that are freely given to us of God. 13 Which things also we speak, not in the words which man's wisdom teacheth, but which the Holy Ghost teacheth; comparing spiritual things with spiritual. 14 But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned.

Answer:

Ok. First, you’re overlooking a truth here. Yes, the brain learns and comprehends and does not readily forget lessons and principles, but there are two things you have need to understand,

1. Once you have responded to the grace gospel and are saved, you cannot become ‘unsaved’ (just like a physical baby cannot be ‘unborn’). At the moment of salvation, one is sealed into Christ by the Holy Spirit. One’s spirit is regenerated and becomes alive to God and to the things that God reveals by His Spirit. Even if a person departs from the truth his spirit remains saved until that day of resurrection.
   
   
2. The things that a saved person starts to tap into are things of the spirit; truths and a connection to God that no unsaved person can experience. The above verse I quoted says that these spiritual things are foolishness to an unsaved person, yet to a saved person these deeper spiritual things produce life and peace and joy. These are the things that an unsaved person cannot understand and conceive because their spirit is dead and is not receptive.

So, as I said, the brain can learn the natural things, the historical things, the tangible things, but until a person is saved, they will never perceive or experience the deeper spiritual things. These spiritual things remain alive as long as they remain connected to the Word and to God. If they depart from the Word and God, these spiritual things will fade away and their spirit (which will always remain saved) will however grow cold and distant to Gods revelations.