No I think a minority of Christian teachers engage in it. But it doesn't have to be a majority to be fairly prevalent. A majority of students probably don't engage in bullying and harassment, but that doesn't mean there's a school in the country where it doesn't happen. When things like reading bible verses over the loudspeaker, coaches baptizing students are a team practice, and inviting guests in who tell students they need to accept Jesus go unchallenged for years and then when they are challenged, the school fights it rather than recognizing the law? I don't think it's very speculative to say that there are lesser violations that are never caught.