There is no discernment in us when we are unsaved. There are no values, there are no standards.
It is our fault we are so ignorant. We did not want to know. We would not listen. Somebody explained it to us, we resisted it. Hear preaching, go to church, read a spiritual book, read the Bible – no, no! This is a wilful ignorance. It is hardness of heart. So if the first word in verse 18 made us feel that the person might not be responsible, the last line gives us the right perspective – because of the hardness, or the wilful blindness in this case, of their heart. And that is the analysis of man.
How can Paul say that the Gentiles have become darkened in their understanding when in fact they make ever increasing progress in science and technology, successfully overcoming one problem after another. In this passage Paul is not speaking of man’s technical prowess, but of his spiritual understanding. Though man is highly acute in the affairs of this world, he is a dunce in matters of the soul. These are the most important matters of all and his skill in other realms only serves to highlight his ignorance in this domain.