The parts of the universe being contingent does not mean that the universe is contingent. In fact, I am going to argue that the universe's existence is necessary. One property of a necessarily-existing thing is that it's impossible to imagine it not existing without falling into a logical contradiction, and that, I put it to you, ladies and gentlemen of the jury, is the case with the universe itself: how can absolutely nothing exist - bear in mind that that means not only physical objects, but time and space? It can't - ergo, the universe exists necessarily.