People until God was revealed, did not understand why we suffer or have joy. They mostly thought that their actions did not affect what would happen to them in the future.
Someone stealing from someone when they are not looking, thinking to themselves about their own interest, without thinking about the other person. They do not realize that their action will bring upon suffering back to them in the future. These people only understand only the immediate gratification from their action, and cannot understand what will happen in the future. This is why God wants us to spread the teachings of the heart.