Christian groups reacted with anger yesterday after a landmark court case effectively outlawed prayers before council meetings.

Former Bideford Town councillor Clive Bone was victorious after joining forces with the campaign group the National Secular Society (NSS) in a legal battle to ban worship in the council chamber. Atheist Mr Bone said it was "discriminatory".

But church leaders, including The Bishop of Exeter, the Rt Rev Michael Langrish, condemned the ruling. "Every time there is a survey of religious beliefs in this country, around 70 per cent of the population profess a faith and to saying private prayers," he said yesterday.

"At the House of Lords we began with prayers this morning. Prayers were said by a considerable amount of peers. I don't think you will find anyone in the House of Lords who will seriously suggest we should end that practice."

The High Court has nevertheless ruled it was unlawful for Bideford Town Council to worship in the traditional way. It said prayers could still be said, as long as councillors were not summoned to attend. Although the court found the prayers did not breach human rights, the Mr Justice Ouseley agreed that the local authority had no legal right to keep them on the agenda.

Bideford Town Council last night said it was considering appealing the decision, however Mr Bone and his supporters were quick to claim definitive victory.

The former councillor said: "It's very good news I'm absolutely delighted.

"I think it makes sense. Things should settle down now and hopefully people will accept and abide by the ruling.

"I know there may be an appeal against the ruling but these things can be expensive. I don't think anybody has limitless pockets."

However Bideford town mayor Trevor Johns echoed the grave concern expressed by the church leaders over the ban saying he was bemused and disappointed by the ruling. He said: "We held two votes on this issue and won both of them by a majority.

"That's what disappoints me. It was a democratic process – you don't go running to the High Court whenever you lose a vote. I just hope the Law Lords have thought this through because there are a lot of ramifications – not just for Bideford but all councils.

"We will discuss the matter at our next full council meeting and assess our response."

The ruling is a crucial test case concerning formal meetings of all councils in England and Wales, the majority of which conduct prayers as part of their meetings.

NSS lawyers argued that council members who were not religious were being "indirectly discriminated against", in breach of human rights laws. Yet the case – launched in July 2010 – was not won on human rights grounds, but on a point of statutory construction of local government legislation.

The judge gave the town council permission to appeal against his ruling, acknowledging that the case raised issues of general public importance.

A town council spokesman said the authority would be speaking to its legal team "to consider our options, including whether to appeal".

Referring to Bideford, Mr Justice Ouseley said: "The council has on two occasions by a majority voted to retain public prayers at its full meetings.

"But that does not give it power to do what it has no power to do."

The judge said the council made attendance at prayers optional "because it recognises that councillors, of whatever religion or none, may not wish to attend prayers as part of a political meeting."

But this turned a council meeting "into a partial gathering of those councillors who share a particular religious outlook, or are indifferent to it or – as in the case of Mr Bone – too embarrassed to leave in public".

Keith Porteous Wood, NSS executive director, welcomed the court ruling, saying: "An increasing proportion of people are not practising any religion, and minority faiths are growing in number and influence."

Prayers had been the cause of tension in a number of local councils and led to difficulties between faiths, underlining the "need for shared civic spaces to be secular and available to believers and non-believers alike on an equal basis".

Mr Porteous Wood said: "This judgment is an important victory for everyone who wants a secular society, one that neither advantages nor disadvantages people because of their religion or lack of it.

"The NSS is not seeking to deprive those who wish to pray the opportunity to do so.

"Our interest in this issue was prompted by a complaintfrom Clive Bone, who felt uncomfortable at having to sit through prayers, homilies and requests for divine guidance while carrying out his formal duties as acouncillor."

Simon Calvert, of the Christian Institute, rejected the NSS claims.

He said the High Court had "taken sides with those whose goal is to undermine our Christian heritage". He added: "It is high time Parliament put a stop to this assault upon our national heritage. What's next? Will prayers at the Cenotaph end up in court?"