Since the definition of God is a hurdle for many of the atheists on this forum such that they are happy that that it is the universe that just is, ...
Firstly I don't think I have ever claimed the universe just is.
But more importantly the whole notion of
the universe that just is is predicated on an assumption that the universe exists within the framework of time viewed in a simplistic manner. In other words that time is constant than uni-linear (i.e goes in one direction only). Now there is no reason to conclude that time is like that, and, of course, if time is actually inextricably linked to the universe then the notion of what happened before the universe existed (implicit in
the universe that just is) becomes completely moot.
But in one respect you are correct Vlad - we don't have anything like a full understanding of the universe which is why we are striving to find out more all the time through research and scientific endeavour. Contrast that with the religionists who refuse to define a god that they appear to have created and then ascribe this god to explain things they don't understand (in a god of the gaps sense) rather than try to actually add to their knowledge.