Is biological evolution a fact or a belief system? If it`s a fact in the same way that in the real number sys?

tem 1+1=2, Why do people like Dawkins (who plagerizes Sagan heavily) write thousands of pages "defending" it? If biological evolution is a fact, & it`s neither "good or evil", why do some evolutionsts say it`s evil to say it isn`t a "fact"? Belief systems,facts,and faith, wow.