I'm finding it hard to believe that people in this thread are saying that the teaching of the history of a socially charged word is something seemingly incomprehensible to 13 year olds yet say that the concept of religion and baptism and everything that comes with it is perfectly understandable for an 8 year old...
I was in a private religious school when I was 10 and was shown a movie where the teacher very explicitly explained that there was use of the word "*******" as a term of endearment and that we weren't to use the word because we couldn't be in such a situation at our age.
Also, given the importance of the subject matter, not sure how this is any different from math. Has to be taught. Responsibility of education in general to do so given the political location of the institution (read: USA) since parents can't be fully trusted to do so. The manner in which it's taught is of course up for debate, but this sort of method likely isn't something new for the teacher with nothing noteworthy happening the last x amount of years the teacher has taught, so my thoughts on why this has come up is due more to sociocultural reasons than educational.
