Is there a faith-based assumption behind Darwinism?
Yes. Darwinists assume as a matter of first principle that the history of the cosmos and its life forms is fully explicable on naturalistic principles. This reflects a philosophical doctrine called scientific naturalism, which is said to be a necessary consequence of the inherent limitations of science. What scientific naturalism does, however, is to transform the limitations of science into limitations upon reality, in the interest of maximizing the explanatory power of science and its practitioners.