I believe the Bible and that settles it. Calvinsts and agnostics like to throw out the "what about those who don't hear the Gospel" problem. The Bible teaches that people go to hell for their sin. In Mark 16:15-16, Jesus tells up what happens to those who believe on Him and what happens to those who do not believe on Him, but does not address what happens to those who never hear about Him - so perhaps there is an opening for God to work in the behalf of those who have not heard.
Under Calvinism everything that happens is God's will. I can't create theoreticals that Calvinists cannot reconcile because Calvinism is unfalsifiable. Under Calvinism everything that happens is God's will. Calvin has created a totally fatallistic (or predetermined) doctrine. Under Calvinism everything that happens was decreed long ago (or set in motion before hand). When I say Calvinism is unfalsifiable, I mean it handles all scenarios - not that it cannot be shown to be false from scripture.
“Creatures are so governed by the secret counsel of God, that nothing happens but what he has knowingly and willingly decreed.” (John Calvin, Institutes of Christian Religion, Book 1, Chapter 16, Paragraph 3)
“…it is vain to debate about prescience, which it is clear that all events take place by his sovereign appointment.” (John Calvin, Institutes of Christian Religion, Book 3, Chapter 23, Paragraph 6)
Calvinism predestines many to hell from before their birth. What could be more monstrous than Calvin's doctrine in this regard. But wait, Calvin adds insult to injury as it is done to give glory to God! 1 John 4:8 says that God is love. Calvin seems to have gotten God's role mixed up with our enemy (2 Corinthians 4:3-4).
“…individuals are born, who are doomed from the womb to certain death, and are to glorify him by their destruction.” (John Calvin, Institutes of Christian Religion, Book 3, Chapter 23, Paragraph 6)
2 Corinthians 4:3 But if our gospel be hid, it is hid to them that are lost: 4 In whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them.