Naturalism is the view that the physical world is a self-contained system that works by blind, unbroken natural laws. Naturalism doesn't come right out and say there's nothing beyond nature. Rather, it says that nothing beyond nature could have any conceivable relevance to what happens in nature. Naturalism's answer to theism is not atheism but benign neglect. People are welcome to believe in God, though not a God who makes a difference in the natural order.
.. People who believe in God think God has put human beings on earth because they think human beings are the best animal, but human beings are just an animal and they will evolve into another animal, and that animal will be cleverer and it will put human beings into a zoo, like we put chimpanzees and gorillas into a zoo. Or human beings will all catch a disease and die out or they will make too much pollution and kill themselves, and then there will only be insects in the world and they will be the best animal.
A wonderful area for speculative academic work is the unknowable. These days religious subjects are in disfavor, but there are still plenty of good topics. The nature of consciousness, the workings of the brain, the origin of aggression, the origin of language, the origin of life on earth, SETI and life on other worlds.. This is all great stuff. Wonderful stuff. You can argue it interminably. But it can't be contradicted, because nobody knows the answer to any of these topics.
A physicist that I know commented that many other scientific disciplines, such as geology, anthropology, astronomy, are also challenged by biblical fundamentalism, but their people seem to be able to get on with their work without worrying unduly. Only Darwinians seem thrown into a frenzy that sends them running to litigation and demanding censorship. His explanation was that it's a rival religion.
Finally, from what we now know about the cosmos, to think that all this was created for just one species among the tens of millions of species who live on one planet circling one of a couple of hundred billion stars that are located in one galaxy among hundreds of billions of galaxies, all of which are in one universe among perhaps an infinite number of universes all nestled within a grand cosmic multiverse, is provincially insular and anthropocentrically blinkered. Which is more likely? That the universe was designed just for us, or that we the universe as having been designed just for us?
In the abstract, it might be tempting to imagine that irreducible complexity simply requires multiple simultaneous mutations - that evolution might be far chancier than we thought, but still possible. Such an appeal to brute luck can never be refuted.. Luck is metaphysical speculation; scientific explanations invoke causes.
I want to pause here and talk about this notion of consensus, and the rise of what has been called consensus science. I regard consensus science as an extremely pernicious development that ought to be stopped cold in its tracks. Historically, the claim of consensus has been the first refuge of scoundrels; it is a way to avoid debate by claiming that the matter is already settled. Whenever you hear the consensus of scientists agrees on something or other, reach for your wallet, because you're being had. Let's be clear: the work of science has nothing whatever to do with consensus. Consensus is the business of politics. Science, on the contrary, requires only one investigator who happens to be right, which means that he or she has results that are verifiable by reference to the real world. In science consensus is irrelevant. What is relevant is reproducible results. The greatest scientists in history are great precisely because they broke with the consensus. There is no such thing as consensus science. If it's consensus, it isn't science. If it's science, it isn't consensus. Period.