Pope warns Church against closing in on itself VATICAN CITY (Reuters) - Pope Francis warned the Catholic Church to not close in on itself at a Mass to mark Pentecost Sunday attended by more than 200,000 people, urging the faithful to be open and present in a new and changing world. The Church should ask itself daily whether it is resisting new challenges and remaining "barricaded in transient structures which have lost their capacity for openness to what is new," he said. "Newness always makes us a bit fearful, because we feel more secure if we have everything under control," Francis said in his homily in front of a packed St. Peter's Square, adding that change can bring fulfillment. The Pentecost Mass marks the day the Church says the Holy Spirit descended on Christ's apostles, or disciples, and is regarded as the birthday of the Church. Francis warned of the threat of an institution which is "self-referential, closed in on herself," and spoke of the courage to "take to the streets of the world" and reach "the very outskirts of existence." Later he toured the square in an open-top white vehicle, greeting cheering crowds and kissing young children. Since his election in March as the leader of the world's 1.2 billion Catholics, Francis has been urging Church leaders to go out into their communities and help the poor and suffering, rather than focusing on internal politics. Morale among the faithful has been hit by a widespread child sex abuse scandal involving Catholic priests and in-fighting and careerism in the Church government or curia. The 76-year-old former Cardinal Jorge Bergoglio of Buenos Aires has given clear signs he will bring a new broom to the papacy, favoring humility and simplicity over pomp and grandeur. He has set up an advisory board of cardinals from around the world to help him reform a Vatican administration which has been held responsible for some of the mishaps and scandals that plagued the eight-year reign of his predecessor Benedict. At a vigil on Saturday evening, Francis said Catholics must become courageous and seek out the people who need help the most rather than sitting around, dissecting theology. Reporting by Catherine Hornby; Editing by Jon Hemming