Why does the Pope have to pick a name?
              The 
                tradition of selecting the name of a saint or beloved predecessor 
                began in the 6th Century. Up 
                until then, popes used their own names. Then came a newly elected 
                pope whose name was Mercurius, after the Roman god Mercury. He 
                decided it wouldn’t do to have a pagan god’s name, 
                so he took the name Pope John II.