Its called Brute fact. That is something that exists but there is no explanation how is possible, or is it. Brute fact can be God, universe, logic, etc.
Colin McGinn discussed the question why anything exists at all. As he talk about the the wuestion of existing, he discovered that there must be things withtout explanation to be able to exlain the things that do have explanation for their existence. So something must be brute.
The problem is that exactly everything can be brute, its dependint of your point of view. Also there is another problem – why some things are brute if the most things are not? What makes God brute?