Do you wonder why normal intelligent people read the Bible, look up the words that they don't understand, read explanations, BUT still don't understand It?

This was my experience - I was trying to find God intellectually, and I thought that the more that I read and studied the Bible the more I would understand.  In fact the opposite happened.  The more that I read and studied the more I realized how little I understood, until I felt that I was in complete darkness.

Why is this?

The reason why people of normal intelligence read the Bible and say 'I don't really understand it' is exactly because God meant it to be so!

The Bible is not like any other book.  It was written by the Holy Spirit and the Holy Spirit must illuminate and enlighten the reader.   It is important to know that the Bible cannot be figured out by my intellect, but the Holy Spirit explains and reveals it. 
It must be pointed out that the Bible is completely closed to the intellect.

So, how can the Holy Spirit explain the Bible to me in my heart?

God taught me that He will not teach the man who is not willing to repent, to obey.  He will not satisfy the merely curious or the proud.  As humans we are sinners in rebellion against God.  Truth does not give itself to a rebel.
In the Garden of Eden, man disobeyed God, rebelled against God.  The Bible says that  "rebellion is as the sin of witchcraft" (1 Samuel 15:23).  Unbelievers are called "the children of disobedience" (Ephesians 2:2; 5:6; Colossians 3:6).  

Until I started obeying the Lord in what I knew to be true, I didn't understand the Bible.  I understood the words, I even knew the right doctrines and I could understand the history... but the essence was missing. Once I started obeying, the Lord showed me more things that I needed to obey and then He showed me that I was lost and then He started turning on the light and now continues to teach me as I read the Bible.  "And they shall be all taught of God"  (John 6:45).  It is truly a marvelous marvelous thing! 
The Bible says "Call unto me, and I will answer thee, and show thee great and mighty things which thou knowest not"  (Jeremiah 33:3)

THE KEY IS REPENTANCE/OBEDIENCE.  To turn to God in repentance and to start obeying (obedience requires action - the fruits of repentance).
"repent ye, and believe the gospel."  (Mark 1:15b)
"But if they obey not... they shall die without knowledge."  (Job 36:12)

"And we are his witnesses of these things; and so is also the Holy Ghost, whom God hath given to them that obey him." (Acts 5:32)