The natural man wants to put God in a box. It is hard for him to comprehend spiritual concepts. It is hard for him to understand that God is a Spirit, that He is everywhere at the same time, that He knows all things including the future, and that He is able to actually dwell within man.

To understand spiritual things, a person needs to be filled with the Spirit.

God made this possible for us when He overshadowed the woman Mary and she brought forth a child, born without sin, so that God could place His name upon Him and dwell within Him from conception. His name is Jesus, the Lord our salvation.

God did this so that He himself could pay the price of the shedding of blood for the sin of the world. He wanted to do this so that He could once again dwell in man and eliminate the separation caused by the sin that began with Adam and Eve. (Acts 20:28, Colossians 1:13-23, 2 Corinthians 5:19, Hebrews 2:14)

We can now be reconciled back to God when we repent of our sins, and we apply the blood He shed for us by baptism in Jesus name. When we enter this covenant with Jesus, He promises to fill us with His Spirit, the Holy Ghost.

When we are filled with the Spirit of God, we are then able to begin to understand spiritual things.

"To wit, that God was in Christ, reconciling the world unto himself, not imputing their trespasses unto them..." - 2 Corinthians 5:19 KJV

"In whom we have redemption through his blood, even the forgiveness of sins:" - Colossians 1:14 KJV

"Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost. For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call." - Acts 2:38-39 KJV

With the Holy Ghost, the Spirit of God, we can understand spiritual things.

"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.

“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. 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.

“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.

“But he that is spiritual judgeth all things, yet he himself is judged of no man.  [Those who are spiritual can evaluate all things, but they themselves cannot be evaluated by others. Thayer’s Greek Lexicon for “judgeth/judged”: to determine the excellence or defects of any person or thing]

“For who hath known the mind of the Lord, that he may instruct him? ["Who hath directed the Spirit of the LORD, or being his counsellor hath taught him?" - Isaiah 40:13 KJV. Greek version of Isaiah 40:13: “Who can know the LORD’s thoughts? Who knows enough to teach him?” Also: Romans 11:34]

“But we have the mind of Christ." [But we understand these things, for we have the mind of Christ. Thayer’s: to be furnished with the understanding of Christ] - 1 Corinthians 2:11-16 KJV (John 15:15, John 16:13-15)