The Christian Socialist Movement has welcomed Ed Miliband’s election as the new leader of the Labour Party.

He narrowly beat his older brother and rival candidate, David, to the top spot by a margin of 1.3% overall in Saturday’s election.

In his first speech to the party as leader, Mr Miliband signalled a clear departure from New Labour and the Blair/Brown years as he declared that a “new generation” had taken control of Labour.

“A new generation has stepped forward to serve our party and in time to serve out country. Today, the work of the new generation begins,” he told the party’s conference on Saturday.

“You have put your trust in me and I am determined to pay that back to you. The first way I will repay that trust is by uniting our party and taking it forward together.”

David Miliband has not yet confirmed whether he will work under his brother in the shadow cabinet. He has until Wednesday to put himself forward for any of the 19 shadow cabinet posts, which will go to vote by MPs on October 7.

David Miliband urged the party to support Ed, saying he would be a “great leader” and warning the party that “unless we are united, we lose”.

Stephen Beer, a spokesman for the Christian Socialist Movement, said the group “very much welcomes” Ed Miliband’s election.

“Most CSM members voted for him as their first preference and Ed has expressed strong support for CSM,” he said.

“He has also highlighted our work to better connect Labour with local communities including church groups. We’re looking forward to working closely with him.”

CSM celebrated its 50th anniversary on Sunday following the Labour Party Conference’s annual church service at Manchester Cathedral. The celebration was joined by Ed Miliband, who said the group was “at the forefront of Labour’s renewal”.