Basically, the objection goes like this. "Telling us 'Goddidit' explains nothing (whether that be creation, basis for morality, etc). So, saying 'Goddidit' isn't really an explanation at all."
But, frequently, atheists will tell us that they "really want to believe." That, "If God would just write in the sky that he exists, that would be enough for me to believe." Etc.
Reppert points out:
In fact examples like these are often used as a basis for challenging believers to provide evidence for belief in God. But why demand that theists provide evidence, if, whatever the circumstances, there couldn't be enough evidence. If "God did it" explanations are really verboten, then it hardly makes sense to complain that theists haven't provided evidence for their position. By definition, that's the one thing they can't do.
So, when the atheist makes claims like the above, saying that "if and only if God would do something like this I would believe" (even though we know this is just a bogus rationalization for their absolute refusal to trust in and believe in God due to their love affair with sin), we must ask him why that would constitute evidence for explaining how the smoke words got in the sky in the first place. To reply, "Well because Goddidit!" isn't an explanation at all.
So, if "Goddidit" isn't a good explanation of how something happened, even if God did indeed do it, then isn't the atheist really just pretending that "evidence" would change his mind? Isn't it more likely that he has a presuppositional bias against God (or, the idea of God!) in the first place? That is, the atheist says that "Goddidit" isn't a good explanation, but he turns around and says that the only evidence that he would accept is evidence where one could only say of it that, "Wow, must be Goddidit!"