Why do you not understand what I am saying? This is a very important question, and our Lord Jesus immediately follows this question up with the answer. Jesus asked the question and gave the answer to this question in John 8:43. He said, "Why do you not understand what I am saying? It is because you cannot hear My word."
So they could not understand what He was saying because they could not hear His word. Now why could they not her His word?
In John 8:44 Jesus gives the answer for this; He said, "You are of your father the devil, and you want to do the desires of your father. He was a murderer from the beginning, and does not stand in the truth because there is no truth in him. Whenever he speaks a lie, he speaks from his own nature, for he is a liar and the father of lies."
The reason they could not here His word, is because they had murder in their heart, and therefore they could only hear lies. Jesus puts anger on equal footing with murder (see Matthew 5:22,23).
Perhaps you are angry about something today, and cannot hear the truth. Relax, take a breath, and spend sometime in scripture alone, not to prove your point, and be right, but to truly know what is right. Do as the Bereans of Acts 17:11 did, if you hear something that bothers you, or your unsure of, or you don't understand; examine the scriptures to see if these things might be so. We cannot see things as they are and hear the truth when we are angry. Also do what Paul said in 2 Corinthians 13:5 "Test yourselves to see if you are in the faith; examine yourselves! Or do you not recognize this about yourselves, that Jesus Christ is in you-unless indeed you fail the test?" Don't just pick the passages out of scripture that you like and discard what you don't like. Your faith must be grounded in the Jesus Christ of scripture alone. Truly look at these things, nothing is more important than the truth. Don't let anger keep you from understanding the truth.
Mike Peek a slave of Jesus Christ