When did Christianity become such a dirty word?

During the course of this tiring election campaign, I've been saddened by the way people seem to freak out over the word, "Christianity." As a country we're told constantly to be a respector of persons, which seems like a good way to be, respector of others' religious beliefs, which, I've never had a problem with doing. But during the past few months, Christianity has been mocked in an unbelievable way. Whether it be by talking-heads in the media, SNL skits, cartoon illustrations, etc. Christianity has taken the brunt of many jokes. I don't know if others feel like Christians think they are perfect, judgemental people, but it's quite the contrary. Most Christians KNOW they're imperfect, that's the first stepping stone to becoming a Christian. When did it become such a bad thing to stand on your moral principles and values? When did it become acceptable to mock others' religious beliefs? This is just something that has been weighing on my mind, and I wanted to get some others' perspectives on this.