You miss the point Chadwell makes - … the naturalist believes that beneath every natural phenomenon there exists yet another natural phenomenon…. The naturalist's answer for the origin of life, therefore, is some natural phenomenon. (Which one is not particularly relevant.) When you ask them how that natural phenomenon came to be, their response boils down to: "It's natural phenomena all the way down!" Does science claim to ‘know’ the origin is some natural phenomenon?
Darwin showed that material causes are a sufficient explanation not only for physical phenomena, as Descartes and Newton had shown, but also for biological phenomena with all their seeming evidence of design and purpose. By coupling undirected, purposeless variation to the blind, uncaring process of natural selection, Darwin made theological or spiritual explanations of the life processes superfluous. Together with Marx's materialistic theory of history and society and Freud's attribution of human behavior to influences over which we have little control, Darwin's theory of evolution was a crucial plank in the platform of mechanism and materialism…
-Douglas Futuyma's Evolutionary Biology (1998, 3rd Ed., Sinauer Associates), p. 5
For example, I don't how the core of Neptune first formed, but it's likely that it had something to do with gravity, its accretion disk, and compression, and not leprechauns making it out of supernatural pixie dust.