God hides things -including the meaning of scriptures -for various reasons. Even though the scriptures are available to read, God had them written and arranged in such a way as to require in-depth study and a strong desire to understand. God is also able to cause you to understand what you read when he decides you should. The timing of revelation of knowledge and understanding is important -just as it is with many other day-to-day things.
Isa 28:9 Whom shall he teach knowledge? and whom shall he make to understand doctrine? them that are weaned from the milk, and drawn from the breasts.
Isa 28:10 For precept must be upon precept, precept upon precept; line upon line, line upon line; here a little, and there a little:
Isa 28:11 For with stammering lips and another tongue will he speak to this people.
Isa 28:12 To whom he said, This is the rest wherewith ye may cause the weary to rest; and this is the refreshing: yet they would not hear.
Isa 28:13 But the word of the LORD was unto them precept upon precept, precept upon precept; line upon line, line upon line; here a little, and there a little; that they might go, and fall backward, and be broken, and snared, and taken.
Consider also....
Mat 13:9 Who hath ears to hear, let him hear.
Mat 13:10 And the disciples came, and said unto him, Why speakest thou unto them in parables?
Mat 13:11 He answered and said unto them, Because it is given unto you to know the mysteries of the kingdom of heaven, but to them it is not given.
Mat 13:12 For whosoever hath, to him shall be given, and he shall have more abundance: but whosoever hath not, from him shall be taken away even that he hath.
Mat 13:13 Therefore speak I to them in parables: because they seeing see not; and hearing they hear not, neither do they understand.
Mat 13:14 And in them is fulfilled the prophecy of Esaias, which saith, By hearing ye shall hear, and shall not understand; and seeing ye shall see, and shall not perceive:
Mat 13:15 For this people's heart is waxed gross, and their ears are dull of hearing, and their eyes they have closed; lest at any time they should see with their eyes, and hear with their ears, and should understand with their heart, and should be converted, and I should heal them.
Mat 13:16 But blessed are your eyes, for they see: and your ears, for they hear.
Mat 13:17 For verily I say unto you, That many prophets and righteous men have desired to see those things which ye see, and have not seen them; and to hear those things which ye hear, and have not heard them
Also....
Mat 7:6 Give not that which is holy unto the dogs, neither cast ye your pearls before swine, lest they trample them under their feet, and turn again and rend you.
It is not extremely clearly expressed in the above -and it seems that God's heart is against those who do not understand -it even seems that he is insulting them by calling them dogs and swine, but it simply means that some things are kept from some people until they are ready to receive them (though, in the case of those who are hostile to the truth, God keeps them from the truth, and gives them over to the misery of their own choices). In fact, keeping things from some is for their benefit -and revealing them too soon can be harmful to them -just as certain things are kept from children until they are ready to understand and can handle the information, and until knowing will not cause them harm. One thing must be known and accepted before another thing can be known and accepted -otherwise a person's spiritual state might become worse then before which could in turn put them in jeapordy.