Pope Francis waves as he boards the plane for his departure after concluding a week-long trip to Brazil, at the air base in Rio de Janeiro on July 28, 2013. The head of the world's 1.2 billion Roman Catholics hammered home his plea for young believers attending World Youth Day (WYD) to "go and make disciples of all nations" as he concluded his trip to Brazil aimed at reigniting Roman Catholic passion. AFP PHOTO / EVARISTO SA