Pope celebrates Mass in Rio cathedral as he encourages Catholics to get out of their churches

Pope Francis is celebrating Mass in Rio de Janeiro's massive cathedral as he begins the culminating weekend of his first international trip, to the church's World Youth Day.

An estimated 1,000 bishops are celebrating the Mass along with Francis and his message is expected to echo what he has told young pilgrims all week: Go out of your churches to the peripheries and spread the faith to society's outcasts.

Francis faces a busy Saturday: After Mass, he goes to Rio's municipal theater to meet Brazilian politicians, businessmen, intellectuals and the diplomatic community. Afterward, he lunches with the country's bishops and then presides over an evening vigil on Copacabana beach that is expected to draw over 1 million young people.

He returns to Rome on Sunday after the final Mass.