The theory of evolution is indeed not 100% assured to be true. Just like the theory of gravity isnt. Science is tentative, there are no absolutes. That doesnt mean u have to have faith in evolution, just like u dont have to have faith in the theory of gravity. Instead of faith we accept the theory that currently descibes the observed events best. If tomorrow apples start falling up the theory of gravity has been falsified and a new theory will be developed that fits the observed phenomenon best. If tomorrow we discover things that falsify the theory of evolution we will have to think of a new theory that fits the evidence. Currently everything has evolution screaming all over it and there is nothing that points to a young earth, a creator or to the account of Genesis, so therefor there can be no other sensible thing to do than accept evolution.