Hundreds of thousands of young people attended the opening Mass of World Youth Day in Madrid's Plaza de Cibeles yesterday (photo gallery). Spanish police have arrested a Mexican chemistry student who allegedly planned to attack a march against Pope Benedict's visit to Madrid. A Spanish nun will leave her convent for the first time in 84 years on Friday to meet Benedict XVI in Madrid (video). A priest in the Indian state of Maharashtra has said that he believes his church was vandalised by devil worshippers. John Allen reports that Fr Thomas Weinandy, an adviser to the US bishops on doctrine, has said that theologians can be a "curse and affliction upon the Church". American pilgrim Rachel Howell describes her experience of the first day of World Youth Day. And Fr Robert Barron offers a preview of his ambitious new television series, Catholicism.