Romans 9:19-20: You Will Say To Me Then, "Why Does He Still Find Fault? For Who Can Resist His Will?"
 You will say to me then, “Why does he still find fault? For who can resist his will?”  But who are you, O man, to answer back to God? Will what is molded say to its molder, “Why have you made me like this?” (ESV)
This passage of Scripture is one of the most difficult for us to grasp. The context for this verse is the hardening of Pharaoh's heart. Paul knows that his readers will have a logical question to the fact that God divinely chooses who he will have mercy on and who he will not have mercy on. If we were not given mercy by God how can he hold us accountable for our sin?
First of all, this is a very valid question. It is one that has caused people much consternation. One of the biggest challenges for us is that many of us have an inadequate view of God. We do not view him as completely sovereign. We insist on things being determined by us. We attempt to direct things and then expect God to fall into line with our will. God does not work that way.
Paul's response is perfect: "Who are you, O man, to answer back to God?" This answer is not only appropriate for this question, it is perfect for every attempt of man to question God. Regardless of what God does he is perfect in what he does because he is God. We must have a view of God that accepts his sovereignty in all things.
Paul gives us a good illustration. God is the potter. We are the clay. God has the right to do as he pleases with what he has created. Part of being clay is that we do not get to say how we are going to turn out. We are at the mercy of the potter's hand. The good news is that the potter is good, and just, and loving, and merciful.
Our God is sovereign. He is also good. Instead of spending our time questioning him, we should repent of our sins, place our faith in Jesus Christ for salvation, and walk in obedience to His perfect will.