Richard Dawkins has said this:
If the alternative that's being offered to what physicists now talk about - a big bang, a spontaneous singularity which gave rise to the origin of the universe - if the alternative to that is a divine intelligence, a creator, which would have to have been complicated, statistically improbable, the very kind of thing which scientific theories such as Darwin's exists to explain, then immediately we see that however difficult and apparently inadequate the theory of the physicists is, the theory of the theologians - that the first course was a complicated intelligence - is even more difficult to accept.... Complicated things come into the universe late, as a consequence of slow, gradual, incremental steps. God, if he exists, would have to be a very, very, very complicated thing indeed. So to postulate a God as the beginning of the universe, as the answer to the riddle of the first cause, is to shoot yourself in the conceptual foot because you are immediately postulating something far far more complicated than that which you are trying to explain.
Dawkins tends to be a little wordy so let me simplify it: he is saying that the explanation for any phenomenon should be less complicated than the thing it tries to explain. Can I say that I find it humorous and somewhat ironic that he would use so many words to explain how things should have a simple explanation? Anyway... according to Dawkins, God would necessarily be far more complicated than the universe and so a Supreme Being as the First Cause is not a satisfactory explanation for the universe. It's a stretch, I know, but he makes this point frequently so he must think it's compelling.
Dawkins' argument suffers from a flawed premise. What objective, testable, scientific principle exists that requires a cause to be less complicated than its effect? He is trying to make a logical argument but it's more like philosophical “wishful thinking.” I utterly reject the notion that an explanation must necessarily be less complicated than what it explains. Such an idea runs contrary to everything we observe.
Consider a painting on a cave wall. How did the painting get there? It's not rocket-science: someone must have painted it on the wall. But isn't a human being more complicated than than the painting? So, according to Dawkins' reasoning, a human painting a picture on the wall isn't a satisfactory explanation.
Of course, Dawkins is not so easily stymied. He's heard this rebuttal before. He claims that the human who made the painting is, himself, the product of simpler beginnings. Through a billions of years long chain of events, the human has evolved from more primitive creatures, which evolved from a single celled creature, which rose naturally from non-living matter, which was fused together from simpler elements, which ultimately came from hydrogen atoms in the big bang. It's a sort of cosmic “butterfly effect” where an expanding cloud of hydrogen in space becomes a painting on a cave wall. How convenient.
The death knell of Dawkins argument lies in our understanding of cause and effect. We've learned that every phenomenon we've ever observed must have sufficient cause to explain it. In every case, the cause is not simpler than the effect but rather is always greater than the effect. In other words, a big bad wolf cannot huff and puff and blow a house down; it takes something like a hurricane or tornado to blow a house down. A ship cannot float unless the weight of the water it displaces weighs more than the ship itself. A bird cannot fly unless the shape of its wings creates more lift under its wings than the bird weighs.
Now, no system is perfectly efficient – there is always wasted energy. If a little input could create a greater output, then something like perpetual motion should be possible. It's not. The cause is always greater than the effect. Always! Therefore, the universe could not have come from nothing. Nothing can only produce nothing. It could never produce something – not even a single atom. The cause of all the matter and energy in the universe must necessarily be something greater than all the matter and energy in the universe.
Dawkins' rhetoric is really nothing more than clever semantics. There is no reason to expect the cause of the universe must be something less complicated than the universe. The exact opposite is true. God creating the universe is by far the most reasonable explanation.