Stephen Bubb, head of chief executives body Acevo, has warned that charities could face political disagreement over their role in the delivery of public services for the first time in 60 years.
In a lecture yesterday, marking 10 years since Bubb was appointed, he set out the development of charitable activity over the past 1,000 years and suggested how the sector would develop in the near future.
He said there had been general consensus between the main political parties since the Second World War.
However, he warned that there was "the danger of charities being drawn into battle between two opposing political ideologies; one that stresses individual responsibility with a much diminished state and less state financing, and one that looks back to state power and provision and disparages charity provision".
"In the current debates over big society, can we be so sure that we have not returned to party political conflict over the role of charities?" he told an audience in London.
"On the one side, there are ideologues on the right who would argue for a dismantling of state action in welfare provision and a return to active citizenship and individual responsibility with voluntary and charity action.
"On the other side, there is increasing evidence that the Labour Party seeks to return to a belief in state action and a rejection of charity expansion."
Bubb said that the concept of big society should be promoted and advocated across party political lines and it would be "unhelpful for the sector to be drawn into party political divisions on our role".
He predicted that the future would bring a bigger and expanded sector.
"We must stand our ground in refusing to be politicised and demanding an active partnership between us and the state," he concluded.