America has been America ever since Vespuci convinced us Columbus was wrong to call it India.
Again, it is very much like the fundamentalist church of my childhood thinking only fundamentalists are "Christian". Since we separated ourselves from the "world" we had no clue that others could be call themselves "Christian" in sincerity. We thought that when others called themselves "Christian" it was an intentional lie.
Nevertheless, since most citizens of the U.S. think when you say "American" you are refering to a citizen of the U.S., I'm sure you understand the reasons for the original comment.