Palm Sunday worshippers were startled to face strong protests against the Pope and calls for his resignation as "an accomplice in sex crimes" outside London's Westminster Cathedral.
The demonstration by 50 members of secularist, women's and gay organisations accused the Pope of "covering up child sex abuse by Catholic clergy" and called him a "protector of paedophile priests".
Some congregants had sympathy with the protest, but others were angry at what they accused of being an attempt to create generalised anti-Catholic sentiment out of the current child abuse crisis which has been growing in scale and strength in recent days.
The Vatican is now at loggerheads with many of its critics, who accuse the Holy See and the Church hierarchy of being completely out of touch and in denial about the depth of the problem.
Radical and progressive Catholics, themselves strongly critical of the Church leadership and calling for sweeping change, including a possible Vatican III Council, have been reluctant to ally with the style of the 'Protest the Pope' coalition.
Instead, they are wanting to use the build-up to Pope Benedict's visit to Britain later this year to push the Church to reverse its denial, open itself to legitimate criticism and commit to real change - including free conversation about teaching on sexuality, women and gay people in ordained and lay ministry, the culture of clerically-based secrecy, enforced priestly celibacy, and the deadening weight of hierarchy.
Some see the response of the Vatican to years of abuse within its ranks as an embodiment of the powerful reactionary and anti-change culture that has grown up in thinly disguised opposition to the reforming winds of Vatican II in 1963-65, which opened the Church, its mission, ministry and liturgy, to renewed faithfulness a changing world.
Meanwhile, the Swiss Catholic theologian, Professor Hans Kung, a leading figure associated with Vatican II, has called on Pope Benedict to issue a "mea culpa" for his part in "covering up decades of clerical sex abuse", both as an archbishop in Munich and as a cardinal in Rome.
Dr Kung, who once taught theology alongside the future Pope at Tubingen in Germany, pointed out last week that Benedict, when he was Cardinal Joseph Ratzinger, had served for many years in Rome as head of the Congregation for the Doctrine of the Faith, during which time he had imposed 'papal confidentiality' on cases of clerical abuse around the world.
In five years as Pope he had "not altered this practice one jot", said Dr Kung.
To the National Catholic Reporter in the USA, he declared: "In his 24 years as Prefect of the Congregation for the Doctrine of the Faith, from around the world, all cases of grave sexual offences by clerics had to be reported, under strictest secrecy ('secretum pontificum'), to his curial office, which was exclusively responsible for dealing with them. Ratzinger himself, in a letter on 'grave sexual crimes' addressed to all the bishops under the date of 18 May, 2001, warned the bishops, under threat of ecclesiastical punishment, to observe 'papal secrecy' in such cases. In his five years as Pope, Benedict XVI has done nothing to change this practice with all its fateful consequences."
Meanwhile, in London, the human rights campaigner Peter Tatchell, one of the organisers of the protest outside Westminster Cathedral, said: "Cardinal Ratzinger threatened to excommunicate anyone who spoke about [these crimes]. This makes the Pope personally responsible for the cover-up."
He added: "Pope Benedict's recent apology is inadequate because he has not apologised for his own failure to act against paedophile priests. He has not said sorry for his own role in covering up their sex crimes.
"The Pope knew about child sex abuse by Catholic clergy. He failed to stop it and he failed to report the abusers to the police. His moral authority is irreversibly tarnished. He should resign."
The Vatican robustly denies any cover up, though it has not opened its records fully on the issue or responded to many specific allegations.
Last night the Most Rev Vincent Nichols, Archbishop of Westminster, defended Pope Benedict from allegations of involvement in a cover-up, claiming that he had actually tightened a number of provisions for dealing with offenders in Church law.
The Catholic Church in England and Wales and elsewhere, has implemented significant reforms, particularly with regard to child protection, but cases of compensation for abuse have also been resisted or settled out of court, and many inside as well as outside the Catholic community believe that much more decisive action and change is needed.
In Italy, one Church figure, Antonio Riboldi, the emeritus bishop of Acerra, declared that the "attack" on the Church over its handling of decades of abuses marked the start of a war "between the church and the world; between Satan and God".
This is precisely the kind of aggressive attitude which others have said goes to the root of the problem. The Guardian newspaper in London and Manchester yesterday declared: "The church seems unable, or unwilling, to accept the depth of the crisis in which it has mired itself and blind to the way its foot-dragging apologies merely exacerbate the damage."
Calling for major reform at the top, the paper added: "In another institution it would be impossible to imagine the survival of a leading figure who was even marginally implicated in such a terrible betrayal of its founding purpose. Indeed, if there were a way of removing Pope Benedict, it might serve to demonstrate the defeat of a generation who, for all the charisma of Pope John Paul II, adopted this disastrous policy of ignoring and often perpetuating the tragedy inflicted on the victims by putting the protection of the church and the needs of the abusers first. But popes do not resign and they are not sacked... So under Benedict, the church hobbles on, haemorrhaging support with each new charge against it."