The Appeal to Mystery Fallacy occurs when the lack of understanding is given as the reason for believing.
Bill Nye answering the question, "Where did the atoms that created the big bang come from?": "This is a great mystery! You’ve hit the nail on the head. No. Uh, the, what was before the Big Bang? This is what drives us. This is what we want to know. Let’s keep looking. Let’s keep searching."