The Scout Association in the UK has announced an alternative version of its membership promise for young people who do not believe in God.
From January, instead of vowing "to do my duty to God", scouts will be able to promise to "uphold our scout values".
The new promise will exist alongside the core scout promise, which has remained unchanged for 106 years.
The Church of England, the Church of Scotland and other faiths have welcomed the move.
The step follows a 10-month consultation.
"I am confident that our relationship with the scouting movement will continue to flourish," said the Bishop of Southwell and Nottingham, the Right Reverend Paul Butler, who leads the Church's work with young people.
"In enabling people of all faiths and none to affirm their beliefs, scouting has demonstrated that it is both possible and I would argue preferable, to affirm the importance of spiritual life."
The Right Reverend Lorna Hood, Moderator of the General Assembly of the Church of Scotland, also welcomed the move.
"I am extremely happy that the Scout Movement has taken this very sensible and inclusive step while ensuring that faith and belief remain a vital element of their ethos," she said.
This is the first time the scout movement has introduced a promise for new members who are atheists - although alternatives to the core promise have existed for nearly 50 years for Hindus, Muslims and Buddhists.
Hindus and Buddhists are currently permitted to refer to "my Dharma" in the scout promise, while Muslims can refer to Allah.
Wayne Bulpitt, the association's UK chief commissioner, said the move signified its "determination to become truly inclusive and relevant to all sections of society".
Mr Bulpitt added the additional alternative promise would not alter the association's commitment to exploring faith and religion as a core element of its programme.
He said he was delighted the move had been achieved with the support of key faith groups as well as the British Humanist Association (BHA).
Andrew Copson, the BHA's chief executive, said the move could only strengthen scouting: "Scouting is an enormously significant youth organisation and in some parts of the country offers the only activities young people have.
"Their initiative sends out a strong signal that the vast majority of young people who do not see themselves as belonging to any religion have values that are worthy of respect and should be explicitly welcomed and catered for in any activity that seeks to be genuinely inclusive."
The association's total UK membership has increased from 444,936 in 2005 to 536,787 this year and includes 77,472 girls
Last month the Guides dropped reference to God from their joining promise, following a consultation that found the movement needed to do more to include the non-religious and those of other faiths.
A ban on atheist scout leaders will also be lifted.
The Scout Association confirmed to the BBC that it would rewrite its equal opportunities policy which currently states: "The avowed absence of religious belief is a bar to appointment to a leadership position."