If we could bring together every person who does not understand the Scriptures, and interview them, we would discover different reasons for why people do not understand the Scriptures, and one of those reasons would be what Jesus said,

“Why do you not understand My speech? Because you are not able to listen to My word” (John 8:43).

These people did not understand because they could not truly listen to Jesus, since they had hard hearts and were not of the Father. As Jesus will go on to show, they were of their father the devil.

Therefore, the spiritual condition of the heart has as much to do with understanding the word as does intellectual capability.