There is no place for God in theories on the creation of the Universe, Professor Stephen Hawking has said.
He had previously argued belief in a creator was not incompatible with science but in a new book, he concludes the Big Bang was an inevitable consequence of the laws of physics.
The Grand Design, part serialised in the Times, says there is no need to invoke God to set the Universe going.
"Spontaneous creation is the reason there is something," he concluded.
In his new book, an extract of which appears in the Times, Britain's most famous physicist sets out to contest Sir Isaac Newton's belief that the universe must have been designed by God as it could not have sprung out of chaos.
Citing the 1992 discovery of a planet orbiting a star other than our Sun, he said: "That makes the coincidences of our planetary conditions - the single Sun, the lucky combination of Earth-Sun distance and solar mass - far less remarkable, and far less compelling as evidence that the Earth was carefully designed just to please us human beings."
He adds: "Because there is a law such as gravity, the universe can and will create itself from nothing.
"Spontaneous creation is the reason there is something rather than nothing, why the universe exists, why we exist.
"It is not necessary to invoke God to light the blue touch paper and set the universe going."
'Eyes of faith'
The book was co-written by US physicist Leonard Mlodinow and is published on 9 September.
In his 1988 bestseller, A Brief History of Time, Prof Hawking appeared to accept the role of God in the creation of the Universe.
"If we discover a complete theory, it would be the ultimate triumph of human reason - for then we should know the mind of God," he said.
But the Bishop of Swindon, Dr Lee Rayfield, said science "can never prove the non-existence of God, just as it can never prove the existence of God."
He added: "Faith is a matter that's outside that.
"But as I look at the universe, and as many people who are much more understanding of cosmology than I, and mathematics, as they look at it, through the eyes of faith, they see a universe which is still very coherent with what we believe about God and His nature."