Romans 1:21-25, 28

They knew God, but they did not give glory to God or thank him. Their thinking became useless. Their foolish minds were filled with darkness. They said they were wise, but they became fools. They traded the glory of God who lives forever for the worship of idols made to look like earthly people, birds, animals, and snakes. Because they did these things, God left them and let them go their sinful way, wanting only to do evil. As a result, they became full of sexual sin, using their bodies wrongly with each other. They traded the truth of God for a lie. They worshiped and served what had been created instead of the God who created those things, who should be praised forever. Amen.

People did not think it was important to have a true knowledge of God. So God left them and allowed them to have their own worthless thinking and to do things they should not do.