It cannot explain the thousands of molecular mechanisms needed in order for change to take place across an entire species, and so on. Contrary to one posters previous quote, science cannot explain the origins of life. It cannot explain the thousands of molecular mechanisms needed in order for change to take place across an entire species, and so on.
This is an evolved form of the Paley Watchmaker argument. It was dealt with in Origin of Species where Darwin illustrated the evolution of the complex eye through intermediate steps that could be seen in lineal species.
In the Articulata we can commence a series with an optic nerve merely coated with pigment, and without any other mechanism; and from this low stage, numerous gradations of structure, branching off in two fundamentally different lines, can be shown to exist, until we reach a moderately high stage of perfection. . . With these facts, here far too briefly and imperfectly given, which show that there is much graduated diversity in the eyes of living crustaceans, and bearing in mind how small the number of living animals is in proportion to those which have become extinct, I can see no very great difficulty (not more than in the case of many other structures) in believing that natural selection has converted the simple apparatus of an optic nerve merely coated with pigment and invested by transparent membrane, into an optical instrument as perfect as is possessed by any member of the great Articulate class.
When it became apparent that larger complex features could be explained by extant and extinct species (the mammalian middle ear is another good example) the creationists moved to systems which could not leave a fossil record, namely cellular microscopic systems such as bacterial flagellum. With zero chance of a fossil record they wouldn't have to worry about those pesky transitional fossils.