So then it is not of him that wills, nor of him that runs, but of God that shows mercy.
Read Chapter 9
When Saul asked forgiveness for his sin he did not receive it, but David, when he confessed his sin, did receive forgiveness. However, it cannot be said on this basis that God judged unjustly by granting forgiveness to the one and withholding it from the other. For the one who looks on the heart knows in what spirit the penitent is making his request and whether it deserves to be heard. And although it is dangerous to try to figure out God’s judgment, yet in the case of unbelievers, who reap the reward of their own minds, it cannot be said that God’s judgment is unjust. Look at the stories of Saul and David and ask yourself what happened to them after God’s judgment. Did Saul do what was right after he was refused mercy? Did he prove that God’s judgment was unjust? Did David after receiving mercy turn his back on God? Or did he remain in him from whom he received mercy? Commentary on Paul’s Epistles.
Paul does not take away the freedom of the will but says that our will is not sufficient unless God helps us, making us compassionate so that we might do good works by the gift of the Holy Spirit…. We cannot will unless we are called, and when we will after our calling neither our will nor our striving is enough unless God gives strength to our striving and leads us where he calls. It is therefore clear that it is not by willing nor by striving but by the mercy of God that we do good works, even though our will (which by itself can do nothing) is also present.
It is clear from this passage that the willing and running are ours, but the fulfillment of our willing and running belongs to the mercy of God. So it is that free will is preserved as far as our willing and running is concerned and that everything depends on the power of God as far as the fulfillment of our willing and running is concerned.