“The real difference between Calvinism and Arminianism is whether God has a purpose when he allows sin and suffering. Again, both views affirm that nothing happens apart from God’s permission. However, Calvinism teaches that God never allows any evil that he has not already determined to work together for our good (Rom. 8:28). Nothing that he allows can terminate in evil. What would we say of a deity who “reluctantly permitted” a terrible disaster or moral tragedy, without a determination to overcome that evil with good? But that takes a plan and that plan must necessarily comprehend the evil that he is to conquer.”
Does Calvinism Make God a “Moral Monster”? – White Horse Inn Blog.