Descartes does an excellent job of establishing doubt as a way to remove any pre-conceived assumptions.
Descartes is like Freud, of great historical interest but basically wrong. Kant does a far better job of establishingly the limits of human knowledge in a logically secure manner.
That aside, yes, it takes faith to accept evolution as truth. But the faith involved is very different from the kind of faith that is involved in religious belief. It is, in fact, the very same faith that leads me to believe that the chair I'm sitting on is real and is there. I cannot (as Kant ably demonstrates) know
1 that the chair is there and real but there is no rational and reasonable way of going through my life without thinking that it is.
1In the specific sense of Philosophical Certainty.