Rom Romans, chapter Epistle to the Romans, chapter 9
So God is merciful to those he wishes to be, and hardens the attitude of those he wants to.9:18. In the Old Testament, this expression is used to describe obstinate rejection of God, such as the experience of the Pharaoh of the Exodus. In Exodus 9 Pharaoh is variously described as choosing a stubborn attitude, or that God gave him a stubborn attitude, or in the passive that he had a stubborn attitude. So this verse in Romans should not be taken to mean that God deliberately hardens people's attitudes and then punishes them for it. The stubborn attitude is a rejection of divine grace.