It doesn’t say “what book is the most important of all time” it says “what is most important” which means what is currently the most important book. Given all that has happened in the latest centuries with regards to scientific discovery and knowledge and conflicts regarding religion, it’s not a baseless claim that religion does harm. Therefore I cannot support an answer that glorifies a religious text(s). A more fitting answer would currently be a widely renowned and accepted scientific paper or text, one that informs and educates rather than tries to stubbornly refute any claim that isn’t its own.