A few relatively simple rules in the beginning gives rise to the the complexity we see. Mathematical simulations of the universe from the moment of the Big Bang have revealed this. I'm not opposed to the idea of some creating force or entity, but I don't believe such a thing is necessary to explain the universe as we know it. It's a complicated topic that I, as a physics layperson, don't fully understand, but that's what I've heard from the physicists that do.