Romans 9:18

God has mercy on whom he wishes. God's mercy and wrath are not influenced by human claims. The "making stubborn" of Pharaoh is explained by 2 Thessalonians 2:10-12. Godet says that Paul is not writing theology here, but answering the proud claims of Jewish pharisaism, showing that no human can place an obligation on God by anything he does or says or is. For a Jew, the contrast between the examples of Moses and Pharaoh are proof, interpreted by the words of God himself. But Paul neither raises nor answers the questions of exactly what the "making stubborn" means, nor the relationship between God "making Pharaoh stubborn," and Pharaoh making himself stubborn. The Jews thought that God COULD NOT abandon them, and that he would not accept the Gentiles.