It is fair because our country was founded on these principles. The men that founded our country had these beliefs and wanted a country that would incorporate them into the countries workings. I am a nonbeliever but do not feel offended or really even consider that it is a problem whenever I say the pledge of allegiance.
I think it is really unfair for non believers. I do not believe in god myself and I always feel awkward recieting the pledge of allegiance. Not everyone believes in god so to say "one nation under god" is unfair and excludes a lot people here in the United States.