Acts 18:6

Acts 18:5-6 (see also Ezekiel 33:8)
But when Silas and Timothy came down from Macedonia, Paul began devoting himself completely to the word, solemnly testifying to the Jews that Jesus was the Christ. But when they resisted and blasphemed, he shook out his garments and said to them, “Your blood be on your own heads! I am clean. From now on I will go to the Gentiles.”

God said to the prophet Ezekiel: “Now, son of man, I am making you a watchman for the people of Israel. Therefore, listen to what I say and warn them for me. If I announce that some wicked people are sure to die and you fail to warn them about changing their ways, then they will die in their sins, but I will hold you responsible for their deaths. But if you warn them to repent and they don’t repent, they will die in their sins, but you will not be held responsible. Son of man, give the people of Israel this message: You are saying, ‘Our sins are heavy upon us; we are wasting away! How can we survive?’ As surely as I live, says the Sovereign LORD, I take no pleasure in the death of wicked people. I only want them to turn from their wicked ways so they can live. Turn! Turn from your wickedness, O people of Israel! Why should you die? (Ezekiel 33:7-11, TLB)

Therefore, Paul says to these unbelieving Jews that he is not guilty of their blood because he has preached the Gospel and warned them of their ways, and the fact that they have rejected the warning, means that Paul is not culpable for their impending judgment.

John Calvin: “By these words, teachers are warned that if they do not want to be guilty of blood before the Lord, they must do whatever they can to bring wanderers back to the way, and that they must not allow anyone to perish through ignorance.” (Acts: Calvin, The Crossway Classic Commentaries, p.309, emphasis mine)

How can this be reconciled with Calvinism? 

Adrian Rogers: “Now if you believe that there is a kind of Predestination and Election that men are going to be saved no matter what, or lost no matter what, this verse makes no sense to me whatsoever.” (Let the Earth Hear His Voice, 2004, emphasis mine) 

That’s exactly what Calvinism teaches:

John Calvin: “At this point in particular the flesh rages when it hears that the predestination to death of those who perish is referred to the will of God.” (Calvin’s New Testament Commentaries: Romans and Thessalonians, p.208, emphasis mine) 

John Calvin: “First, the eternal predestination of God, by which before the fall of Adam He decreed what should take place concerning the whole human race and every individual, was fixed and determined.” (Concerning the Eternal Predestination of God, p.121, emphasis mine) 

John Calvin: “God had no doubt decreed before the foundation of the world what He would do with every one of us and had assigned to everyone by His secret counsel his part in life.” (Calvin’s New Testament Commentaries: Galatians, Ephesians, Philippians and Colossians, p.20, emphasis mine) 

John Calvin: “…the reason why God elects some and rejects others is to be found in His purpose alone. … before men are born their lot is assigned to each of them by the secret will of God. … the salvation or the destruction of men depends on His free election.” (Calvin’s New Testament Commentaries: Romans and Thessalonians, p.203, emphasis mine)

Throwing Calvin’s words right back at him, we might as well ask, “Are you saying that everything that happens does not please God? If they perish through ‘ignorance,’ are you saying that God is not ‘pleased’? Therefore, anyone who shirks their Christian duty, which results in someone else perishing through ignorance, must it secretly be according to the pleasure of God’s predestination?” And, of course, God is not pleased when anyone perishes since He desires all to come to “repentance” and to be “saved.” (2nd Peter 3:9; 1st Timothy 2:3-4; Ezekiel 33:11)