How to argue against this claim

[Anomalocaris]

You do realize that most of the atheists here started off as Christians, right? And something "science cannot explain" isn't god by default, ever heard of "god-of-the-gaps"?

Yeah. Isn't kind of like "science of the gaps"--"I don't know how the cosmos came about, but we'll discover that some day." Or "You think that you experience God, but you really don't. You're just crazy or lying because that's impossible." Or "The cancer didn't really just go away. It was just a physical abnormality or the person is lying because it's impossible."

Yes, it is the science of the gaps. The difference is the God of gap claims the gaps can be pretend to be crossed by stepping on just one vacuous word, God, and once you uttered it, you can pretend you are on the other side, even though you are still where you started.

The gap of science says there is a gap, you can't cross it, maybe you never could, but science which has demonstrably succeeded before, will try to help you cross it if you ever could.

Science of gap - honest effort based on track record.

God of gap - bull now, bullshit forever, bullshit enough, and you forget there exist such a thing as truth, and you wouldn't remember the gap still gaps before you.