The Bible is not a pamphlet explaining the existence of God. It is a complicated compilation of historical events, personal dramas, poetic expressions and spiritual analysis. God Himself is not easy to fully grasp in one reading.
The existence of God and the plan of Jesus Christ was called a mystery by Paul (14 times in Romans, 1 Corinthians, Ephesians, Colossians). Clues and evidence along the way have given us the full revelation found in the Bible.
As complicated as this mystery remains, it’s amazing how easy the Bible is to understand. Like any great text it takes time and the help of teachers.
The other difficulty with understanding the Bible is more the fault of the listeners. The apostles too wondered by Jesus was hard to understnad.
The disciples came to him and asked, “Why do you speak to the people in parables?”
He replied, “The knowledge of the secrets of the kingdom of heaven has been given to you, but not to them. Whoever has will be given more, and he will have an abundance. Whoever does not have, even what he has will be taken from him. This is why I speak to them in parables: “Though seeing, they do not see; though hearing, they do not hear or understand. In them is fulfilled the prophecy of Isaiah:
“ ‘You will be ever hearing but never understanding; you will be ever seeing but never perceiving. For this people’s heart has become calloused; they hardly hear with their ears, and they have closed their eyes. Otherwise they might see with their eyes, hear with their ears, understand with their hearts and turn, and I would heal them.’ But blessed are your eyes because they see, and your ears because they hear.'" Matthew 13:10-16
People hear what they want to hear. They see with their eyes, but not with their minds. They hear with their ears, but not with their hearts. They have become hardened, calloused and stubborn. Parables sometimes need explanation and Jesus always offered one. He chastised his disciples for not listening and seeing the context of what Jesus was explaining through story and example.
Parables are actually a more effective way of communicating. Think of the lessons we learned through movies or how a speaker opens with personal story then relates back to it as an example of the lesson he is trying to communicate. Stories, since man started communicating, have always been the preferred way of relating complicated messages through practical applications.
Parables start as mysteries that catch your interest, then, once you understand their point, have a sort of “ah-ha” kind of revelation to them.