Unbelievers are hardly in any position to see this with their "God cannot exist because bad things happen" mantras.
So. How's about trying to put the argument differently to them?
Try saying " Okay, let us assume that God is not good for the reasons you are presenting. But that does not remove any arguments as to His existence. His existence is not dependent on His nature. So if you do not believe in a loving God - start by offering Him the deference and respect that He is due as the most powerful being in the universe.
We'll get to the 'why He is good bit' - later!
I dunno for sure. It may prove helpful for some.
