Christians are called to be revolutionaries, changing the world one heart at a time, Pope Francis said. "A Christian who is not a revolutionary today isn't a Christian," the pope said June 17 during a conference that quickly turned into a rally for evangelization and care of the poor. More than 10,000 people gathered at the Vatican -- most in the audience hall, but also in the parking lot outside -- to listen to Pope Francis kick off the annual Rome diocesan convention, a three-day gathering of priests, religious and laypeople to set pastoral priorities for the coming year. Speaking for 30 minutes without a prepared text, Pope Francis repeatedly called upon Rome's Catholics to take seriously their responsibility to bring God's love and the promise of salvation to the poor, the sad and the suffering. The revolution started 2,000 years ago by Jesus, who accepted death in order to save humanity, is the longest lasting revolution in history and the one with the greatest impact on the world because it focused not on territory or power, but on changing human hearts, the pope said.