Should Teachers "Live" Their Subjects?

Is it important for a teacher to "live" his or her subject? Should passion for a subject be a requirement before we teach it? For example, should a social studies teacher be someone who is active in civics and fascinated by history? Does teaching history require that someone geeks out about it and reads books on history and constantly sees the world through that lens? Should a science teacher be someone who actually spends time outdoors and observes the natural world? Should a science teacher be someone who experiments often and pays attention to the five senses? Is a passion for scientific discovery a prerequisite for teaching science? Should a language arts teacher be an avid reader? Should that person be a writer as well? Should we be able to walk in and check out his or her bookshelves? Can you teach language arts well without being the kind of person who thinks about the construction of an argument or the power of the language or the themes and motifs that emerge even while watching a movie? Should a math teacher be someone who likes to play with numbers? Does teaching math require someone who is passionate about posing questions and solving problems through a logical lens? Do you have to love math to teach it? And if so, what does that mean for elementary teachers who teach all subjects?