Nothing in science is ever proved, only provisionally accepted or disproved. Though faith has some hold in religion: while no doubt scientific knowledge is thoroughly grounded in observation, we have no time individually to verify everything that provides the theoretical background to what we're investigating, so we to some extent do rely on "faith": the faith that the world is there, the faith that the world is observable, the faith that observation is ceteris paribus repeatable - and, in some ways, there are axiomatic and probabilistic elements there also.