Since the big decrease in Mass attendance and priests and nuns abandoning their vocations occurred right after Vatican II (1965), maybe it was the media and liberal's misinterpretation of Vatican II which started this decline.  I'm sure that Pope St. John XXIII never expected this outcome from his Council, and probably wouldn't have adjourned it if he knew that the media and the liberals would so deform it with their misinterpretations.  There was nothing wrong with the Council, but liberals hijacked its implementation.  Whatever else he was, John was a loyal son of the Church.