Leader? The pope is not just a leader. He is the divine representator of (for) god on this earth. He is the appointed successor to saint Peter, the guy chosen by Jesus himself as be the "frontman" (what Dave Grohl is to the foo fighters for you heretics ;) ) of the apostles and the bearer of the keys of heaven.
Or, at least, that's according to true catholics.
Anyway, the pope is not just a leader.
I was trying to be funny, not pedantic.. I failed. :/