[Note: I watched some of a recent online interview with Dr. Rauser — just enough to get the gist — and wrote the following about his argument this morning. I wasn't aware that the debate with Loftus was already tonight. Maybe the following will be useful for those who watch it. I should also add that there may be additional details to Rauser's argument that this doesn't cover.]
In the book God? A Debate between a Christian and an Atheist (p. 124), William Lane Craig replies to the argument:
If God exists, gratuitous suffering does not exist
Gratuitous suffering exists
Therefore, God does not exist
by means of a so-called “Moorean shift,” in this case by arguing instead:
If God exists, gratuitous suffering does not exist
God exists
Therefore, gratuitous suffering does not exist.
(This is called a Moorean shift after the British philosopher G. E. Moore, who famously turned arguments for philosophical skepticism — e.g., that you might be a brain in a vat — around in this manner.)
What Craig is doing is pointing out that one can deny a premise of an argument if doing so seems more reasonable than accepting its conclusion. He thinks the existence of God is more certain than that of gratuitous suffering. Therefore, rather than accepting the conclusion that God does not exist, he finds it more reasonable to deny the claim that gratuitous suffering exists. Of course, we can easily disagree with Craig's use of this strategy here. The existence of gratuitous suffering (suffering that is morally unjustified and which therefore an all-powerful and perfectly good being would not allow) seems far more certain than the existence of the being himself. So there are good and bad uses of this strategy.