Wouldn’t the atheist have to argue:
- If gratuitous evil exists, then God goes not exist
- gratuitous evil exists
- therefore God does not exist.
But to use evil as a reason to doubt theism, the atheist would have to defend premise 2, that gratuitous evil exists. If premise 2 is not true, then there is no reason to think that God does not exist.
But Trevors’ point (if I understand him) is that in defending premise 2, that gratuitous evil exists, the atheist seems to be committed to the idea that a real (non-subjective) evil exists, and therefore good would have to exist. But many think that good (or objective moral values) could not exist without God (the agnostic philosopher of science, Michael Ruse, for instance). So, the existence of (moral) evil actually provides a reason to believe in God (and his goodness since, goodness is based in God’s essentially just, loving nature).
Now the skeptic could do what Spock does and use the term “evil” to mean “suffering”, as opposed to moral evil, which is a much better argument, though it also has its problems and ultimately, does not provide a reason for doubting God’s goodness, power, or existence.God may have morally sufficient reasons (or a justifying reason) for allowing the existence of suffering. For a skeptic to argue that suffering disproves (the Christian) God, he would have to show that God can
not have such a reason for allowing the existence of evil. This is a heavy burden of proof that I don’t see how he can meet.