Pope Francis on Friday urged the troubled Catholic Church not to give in to "pessimism" and to find new ways of spreading the faith "to the ends of the earth".
"Let us not give in to pessimism, to that bitterness that the devil offers us every day," the 76-year-old Argentinian told an audience of the world's cardinals on his third day in office.
In a reference to the declining number of worshippers in many parts of the world, he urged the cardinals to find "the courage to persevere and also to find new ways to bring evangelisation to the ends of the earth".
Francis said he and they were "elderly", but old age brought wisdom.
"Let us give this wisdom to young people like good wine that gets better over the years," he said.
The first Latin American pope in history hailed his predecessor Benedict XVI's historic resignation as a "courageous and humble act".
Benedict, who last month became the first pope to stand down for 700 years, had "lit a flame in the depth of our hearts that will continue to burn", he said.
The new pope wore white papal vestments but also plain black shoes, not the red shoes favoured by his German predecessor, for the address in the ornate 16th-century Clementine Hall in the Apostolic Palace at the Vatican.
Jorge Mario Bergoglio has signalled his will be a more simple papacy, stripped of the fineries enjoyed by his predecessors, and has called for a return to the Church's roots.
Yesterday, he gave a stark warning that the Church, wracked by scandal and Vatican infighting, risked becoming just another charitable organisation if it strayed from its true mission.
The speeches are part of a series of events leading to his inauguration mass on Tuesday -- a significant date in the Catholic calendar because it is the Feast of St Joseph, the patron saint of the universal church.
The new pontiff is also due to meet his predecessor, who has withdrawn to the papal summer residence in Castel Gandolfo, in the coming days.