New Labour leader Ed Miliband does not believe in God, he has said.
Mr Miliband had previously said his religious views were a "private matter", and his declaration means two of the three leaders of major British political parties are self-proclaimed atheists.
Deputy Prime Minister Nick Clegg also confirmed he does not believe shortly after being named Liberal Democrat leader, while David Cameron last year said religious faith was "part of who I am" but admitted he did not go to church regularly.
The Labour leader's atheism puts him in stark contrast to his predecessors Tony Blair and Gordon Brown, for whom religion was a central part of their lives.
In an interview on Radio 5 Live, Mr Miliband was asked by presenter Nicky Campbell: "Do you believe in God?"
The Labour leader replied: "I don't believe in God personally, but I have great respect for those people who do. Different people have different religious views in this country. The great thing is that, whether we have faith or not, we are by and large very tolerant of people whatever their view."
Mr Miliband and brother David are of Jewish descent, but religion did not play a large part in their upbringing by their Marxist father Ralph Miliband.
David has said publicly he is an atheist, and was the target of some criticism for sending his son to a Church of England school.
Despite spin doctor Alastair Campbell's famous comment to reporters that "we don't do God", Mr Blair has confirmed since leaving power that his religious faith was "hugely important" to his premiership. He said he did not speak publicly about his belief while in office out of fear voters would think him a "nutter".
Since leaving Downing Street, he has converted to Roman Catholicism, and in his recent memoir, A Journey, he wrote: "I have always been more interested in religion than politics."