Evolution is science because scientific hypotheses are testable. These hypotheses make predictions, and the predictions can then be tested against the available evidence, and therefore they can be falsified. For example, if an evolutionary hypothesis suggests that amphiabians evolved from a reptile, for example, this hypothesis predicts that reptilian fossils will be found in an older layer of rock than amphibian fossils. The available evidence shows the exact opposite, i.e. amphibian fossils are older than reptilian fossils. Therefore this evolutionary hypothesis has been tested and falsified. Other evolutionary hypotheses must also be testable to be considered scientific.
To be fair, some scientists do act religiously, and we call them dogmatists. Cladists for example are dogmatists, and many scientists, including Ernst Mayr have made fun of the cladists and called them religious. So, your accusation has a grain of truth but evolution is not a religion, because it is supported by a mountain of evidence and it has been tested for over a hundred years without being falsified. It is true that evolution is not observable, but then elementary particles are not observable either. We only see indirect evidence of particles like protons and electrons when they collide with matter and leave traces of themselves. According to your claim electrons and protons are not real and physics is not science. It is not a surprise that creationists are forced to reject not only biology but all disciplines of science.