Jesus spoke parables, but He did not give the interpretation to everyone. Therefore, when the disciples were private with Him, they asked Him about the interpretation, and He gave it, but first notice how He prefaced His explanation,
But when He was alone, those around Him with the twelve asked Him about the parable. And He said to them,
“To you it has been given to know the mystery of the kingdom of God; but to those who are outside, all things come in parables, so that, ‘Seeing they may see and not perceive, and hearing they may hear and not understand; lest they should turn, and their sins be forgiven them’” (Mark 4:10–12).
Those who have the right heart will grow in their knowledge of God’s word, but those whose hearts are not right, will not grow, and you can see this in our world today.
You may find an atheist, for example, who has read the Bible, but listen to him try to interpret it, and you will discover a serious lack of understanding the word of God.