The Pope stepped into the debate over God and the universe today - saying that science cannot explain the "ultimate meaning" of human existence.
The Pontiff told an audience of religious leaders from different faiths that the human and natural sciences provide us with an "invaluable understanding" of aspects of our existence.
But he said the disciplines cannot satisfy the "fundamental" question about why we exist.
"They cannot satisfy the deepest longings of the human heart, they cannot fully explain to us our origin and our destiny, why and for what purpose we exist, nor indeed can they provide us with an exhaustive answer to the question 'Why is there something rather than nothing?'," he told his audience at St Mary's University College in Twickenham, south west London.
The Pope's message comes after Professor Stephen Hawking argued in his new book that God did not create the universe.
In his speech, the Pope argued that genuine religious belief leads people beyond "present utility" towards the transcendent.
"It reminds us of the possibility and the imperative of moral conversion, of the duty to live peaceably with our neighbour, of the importance of living a life of integrity," he said.
"Properly understood, it brings enlightenment, it purifies our hearts and it inspires noble and generous action, to the benefit of the entire human family."
He added that co-operation and dialogue between religions throughout the world called for "mutual respect" and the freedom to practise religion without suffering persecution.
The Chief Rabbi Lord Sacks, who was present to hear the Pope speak, said he had emphasised the importance of inter-faith relations.
"I think he could sense that around the room, from all the faiths, there was a real genuine warmth and friendship," he said.
He said the Pope is a "gentle man" with a "large vision".
"I found his words very touching. I found him very approachable and very human. I thought he was really encouraging us as a whole to continue this inter-faith relationship."
He said that, in a private meeting with the Pope, the Pontiff had emphasised the value he gives to relations between the Catholic and Jewish faiths.