Darwin's theory addresses the origin of the species, i.e. the development of a diversity of life from common ancestors. By what standard does that fall outside of science?
Leaving the scientific probity of the theory of evolution aside, -- I don't think that arranging similar extinct species along a time line proves that one species genetically produced the other, -- it is legitimate science to look into origin of species, advance hypotheses, and prove facts. Once science is done, it is a domain of a theologian, not a scientist, to relate the creation to the Creator, or even to the absence of a creator. Darwinism had a significant social impact not because we now better understand how to breed dogs, but because it purported to say something about God, and this was intellectually fraudulent.