Romans 9:20

‘No but, O man, who are you who replies against God? Will the thing formed say to him who formed it, “Why did you make me thus?” '

Paul's response to the questions is illuminating, both in what he does not say and what he does say. He does not attempt to marshal arguments which he could have used had he believed them, such as 1). that God acts on the basis of what He foresees in men (whether belief or unbelief), or 2). that God has some other way of saving Jews who reject Jesus as the Messiah. These are arguments which some among modern man would put forward. But Paul seemingly does not accept them. Rather he simply declares by his questions put to the ‘man', that he knows of no explanation, indicating thereby that he has no valid argument apart from what the Scriptures have stated. He then simply challenges whether they as human beings are in any position to reply against God, or disagree with Him. And he does it on the basis that the creature cannot say to his Creator, ‘why did you make me thus?', which is a loose rendering of Isaiah 45:9. The Creator, in other words, has sovereign rights to do what He will with His creation which no one can deny, and He can choose to do with His creatures what He will.

‘O man.' This signifies, in context, puny man as compared with the mighty God, as puny man seeks to contest what God chooses to do.