Fundamental Question

This is a question I have (and many others have had) that I wish could be definitively answered. There are many ways to phrase it; one way to put it is: this universe, full of galaxies, full of stars and yet full of darkness, did it come into being by accident or the volition of God?

Mystery and Existence

The term 'mystery' means that which is unknown, indefinite, shadowy. People like to solve or uncover mysteries, that is, find the truth or the facts within or behind mysteries; render the stuff of mystery easily understandable.
The term 'existence' refers to the 'isness' of something, that is, that a thing, in actuality, is. A unicorn may not exist, but lots of drawings of unicorns do exist.
The phrase 'mystery of existence,' in essence, means that it is mysterious for things to be as they are in this world. The cosmos is not self-explanatory.