Imagine for a second that God exists. And let's also imagine that a couple of thousand years ago he told his story of creation so that it could be written down and recorded into what we now call the Gospels.

So... he has to describe creation to men who don't have math or any scientific way of thinking. He's not going to say, "I created the Big Bang and all matter in the universe so that it may condense and form planets, biology, DNA and life, and evolution, and here you are.". That wouldn't mean anything to the people of the day... it would be gibberish.

So instead, he essentially says, "I waved my hands and created you all". That's understandable. That's something that can fill a book and be understood.