Pope Francis celebrated the last Mass of his trip to Brazil on Sunday before more than a million people gathered on the beach in this city, the national flags of Catholics from around the world hoisted in the air as a chorus of Brazilian priests belted out songs before the multitude. It was a vibrant display of the Vatican’s ambition of halting the losses of worshipers to evangelical churches and the rising appeal of secularism.

Among world leaders who engage in twiplomacy - the use of Twitter for diplomatic relations - President Barack Obama wins superlatives for the most followers but Pope Francis is the most influential, according to a new survey by Burson-Marsteller. The global public relations and communications firm found that more than three-quarters of world leaders are on Twitter - the online social networking service that limits messages known as tweets to 140 characters.

With all eyes on Brazil during the Pope’s visit, protests are planned in Rio throughout the week to reiterate demonstrators’ grievances, including insufficient but expensive public transportation, government spending on mega-events like the World Cup, and political corruption. A protest took place in Rio the first day of the Pope’s visit, when around 2,000 people demonstrated outside of the governor’s palace where the Pope had attended an event.

Pope Francis was greeted by enthusiastic crowds in Rio de Janeiro as he returned to his native continent for the first time as pontiff, but was involved in a security scare as his car took a wrong turn on the way from the airport. Later petrol bombs were thrown and protesters accused riot police of an unprovoked attack in clashes outside the presidential palace.

Pope Francis' diplomatic skills were put to the test Monday as his political nemesis, Argentine President Cristina Fernandez, asked him to intervene in the dispute with Britain over the Falkland Islands. There was no immediate comment from the Vatican as to whether the Argentine-born Francis would accept her request, which was made during his inaugural audience with a visiting head of state on the eve of his installation as pope.