“Not everybody in the neighborhood is Christian and many people do not wish to see such a flagrant display of your beliefs,”
Obviously, not all of her neighbors are American or believe in American values. What if the next time she decorates her home it’s with lights that spell out “some of my neighbors are intemperate jerks”
My guess is that the author of the letter is pretending to speak for some of the neighbors when in reality speaking only for him/herself.