Spain's Roman Catholic church has in effect placed itself in the frontline of political opposition to José Luis Rodriguez Zapatero's six month-old government by calling the first major demonstration to protest against its plans to introduce gay marriage, make divorce and abortion easier and amend religious education in schools.
The demonstration, to be held in Madrid in December, is part of the church's attempt to build a grassroots movement against the government's social reforms.
According to church documents published in Spanish newspapers yesterday, letter-writing campaigns and petitions are being organised through its national network of dioceses and parishes.
"In the month of December there will be a great demonstration in Madrid, called by all the dioceses and Christian movements, associations and groups," said a letter from the archbishopric of Alcála de Henares, 30 miles from Madrid.
The demonstration would concentrate on "the family, life and education".
It went on to accuse Mr Zapatero's government of doing "little negotiating" with the church on its future plans.
The government has already scrapped an education bill approved by the previous, conservative People's party government which would have made religious education a compulsory exam subject for Spanish school children.
Although Mr Zapatero's government has not yet said exactly what plans it has for religious education, it has indicated that schools will still offer non-compulsory religion classes by teachers appointed by Roman Catholic bishops but paid by the state.
It has also proposed that religious classes may be taught by people from other churches or religions.
It also wants to introduce a new compulsory subject called "education in citizenship" to teach "democratic values".
Church leaders have argued that the new subject may be used to turn students away from the church or to "indoctrinate" them in the government's own beliefs.
A recent opinion poll for the leftwing Cadena Ser station said 61% of Spaniards supported the government's most controversial new measure, the legalisation of gay marriage.
And 72% said the Roman Catholic church, which currently receives an estimated €140m (£95m) from state coffers, should be left to finance itself.
Among the reforms being prepared by the government is one to give other Christian churches - Anglicans and other Protestants - and Jews and Muslims some of the privileges currently enjoyed exclusively by the Roman Catholic church. Although some Protestant church leaders have welcomed this, a spokesman for the archbishopric of Alcála de Henares said that other confessions would be joining the protest.
"There are others who are worried about some of the measures too," he said.
Yesterday Cardinal Renato Martino, president of the pontifical council for justice and peace, dismissed accusations that the church interfered with social issues.
"The church ... is really the one which defends the secular nature of the state, urging all to render to God what is God's and to Caesar what is Caesar's," he said in Rome.
His comments came as the Vatican published a 525-page work on the social teaching of John Paul II and other recent popes intended as a handbook for the guidance of, among others, politicians.
In one of the most robust denunciations ever, the Vatican described abortion as a "horrendous crime" and a "particularly serious moral disorder". It told Catholics that they had "a grave duty of conscience not to cooperate, not even formally, in practices which, although permitted by civil legislation, are contrary to the law of God."
"Such cooperation in fact can never be justified, not by invoking respect for the freedom of others nor by appealing to the fact that it is foreseen and required by civil law."
But when he was asked if Catholics could vote for a politician who backed legalised abortion, the Vatican spokesman, Dr Joaquin Navarro-Valls, said: "[the Holy See never gets involved in electoral or political matters directly."