Image caption Cardinal Keith O'Brien has made a reputation with his robust defence of traditionalist Christian teaching

The leader of the Catholic Church in Scotland, Cardinal Keith O'Brien, has used his Easter message to attack "aggressive secularism".

It was an issue Pope Benedict warned about on his state visit to Britain last year.

Cardinal O'Brien said the enemies of Christianity wanted to "take God from the public sphere".

The cardinal has made a reputation for his robust defence of traditionalist Christian teaching.

But BBC religious affairs correspondent Robert Pigott said even by Cardinal O'Brien's standards his Easter sermon constituted a vehement and outspoken attack on secularism and what he described as the enemies of the Christian faith in Britain and the power they currently exert.

Religion must not be taken from the public square Cardinal Keith O'Brien

The Cardinal called on Christians of all denominations to resist the efforts of such people to destroy Christian heritage and culture.

In a reference to equality legislation preventing discrimination against homosexual people, Cardinal O'Brien denounced what he claimed was the way Christians had been prevented from acting in accordance with their beliefs because they refuse to endorse such lifestyles.

The Cardinal said: "Perhaps more than ever before there is that 'aggressive secularism' and there are those who would indeed try to destroy our Christian heritage and culture and take God from the public square.

"Religion must not be taken from the public square.

"Recently, various Christians in our society were marginalised and prevented from acting in accordance with their beliefs because they were not willing to publicly endorse a particular lifestyle.

"Yes - Christians must work toward that full unity for which Christ prayed - but even at this present time Christians must be united in their common awareness of the enemies of the Christian faith in our country, of the power that they are at present exerting, and the need for us to be aware of that right to equality which so many others cry out for."

Cardinal O'Brien reminded his congregation at St Mary's Cathedral in Edinburgh of the plea by the Pope that Christians of different denominations should rediscover their common ancestry to unite in resisting the sidelining of religion.

Dr Evan Harris, a campaigner for the separation of Church and state, branded the Cardinal's remarks "paranoid and unjustified".

He said: "It is not 'aggressive' to call for an end to religious privilege in society and many people of faith agree with the call for the state to be neutral in religious matters."

The Anglican archbishops of Canterbury and York, Dr Rowan Williams and Dr John Sentamu, were also delivering Easter messages on Sunday.

The Catholic archbishop of Westminster, the Most Reverend Vincent Nichols, was speaking of his hopes for peace in conflict-hit countries such as Libya, Syria, Afghanistan and Ivory Coast.