I know I'll sound like a total religious nut, but I think that the chorus is about St. Peter, the first Pope of the Catholic faith. Peter means "rock" in Hebrew, and Jesus put him as "the leader of a flock" and Jesus even is described as a shepherd and that we are his flock. And Peter is "called to be a rock" literally his name. "For those below" I think refers to the belief that Peter holds the keys to Heaven, allowing "those below" into Heaven. That's about all that theory covers.
I know I'll sound like a total religious nut, but I think that the chorus is about St. Peter, the first Pope of the Catholic faith. Peter means "rock" in Hebrew, and Jesus put him as "the leader of a flock" and Jesus even is described as a shepherd and that we are his flock. And Peter is "called to be a rock" literally his name. "For those below" I think refers to the belief that Peter holds the keys to Heaven, allowing "those below" into Heaven. That's about all that theory covers.