The changes Francis brought to the papacy were more than skin deep. He opened the church to the outside world in ways none of his predecessors had done before.

As Pope Francis remains in critical condition fighting a complex respiratory infection and double pneumonia, world and interfaith leaders are offering well wishes and prayers for the recovery of the Argentine pontiff.

What happens when a pope is incapacitated? Is he still pope? Pope Francis' age and prolonged illness have raised questions about whether he might resign, and revived interest about how papal power is exercised.