Rom 9:18 Therefore hath he mercy on whom he will have mercy, and whom he will he hardeneth.
Rom 9:19 Thou wilt say then unto me, Why doth he yet find fault? For who hath resisted his will?
Rom 9:20 Nay but, O man, who art thou that repliest against God? Shall the thing formed say to him that formed it, Why hast thou made me thus?
Rom 9:21 Hath not the potter power over the clay, of the same lump to make one vessel unto honour, and another unto dishonour?
Is this the way an apostle of God would answer the question?
Q. If there is a God and man does not have an autonomous, libertarian free will, then God is responsible for evil. How can anyone justly be held accountable for their actions?
A. Dude, you got me there!
No! Paul raises the very question that his statements demanded and then answers it in a way that reflects the proper perspective of Creator-creation relationship.
Q. If man cannot resist God's will, then he cannot be responsible for his actions.
A. Oh man, who are you to judge God? Upon what basis can the created thing put the Creator on trial and rightly judge him by asking "Why did you make me like this?"
...
"Oh, man, who are you to answer back to God"? This is Christian apologetics at its finest. Let the atheist whine and complain about you God being a "monster" and all that. Without the God of the Bible, upon what basis can the atheist make a moral argument against God from his own moral relativism?