A group of 19 Catholic priests and academics have appealed to bishops to declare Pope Francis a heretic, in the latest ultra-conservative broadside against the pontiff over a range of topics from communion for the divorced to religious diversity.
The most prominent of the group is Father Aidan Nichols, a 70-year-old British priest of the Dominican order who has written many books and is one of most recognised theologians in the English-speaking world. The others are less well known.
"We take this measure as a last resort to respond to the accumulating harm caused by Pope Francis's words and actions over several years, which have given rise to one of the worst crises in the history of the Catholic Church," they said in a 20-page open letter.
The letter attacks Francis for allegedly softening the Church's stance on a range of subjects. They say he has not been outspoken enough against abortion and has been too welcoming to homosexuals and too accommodating to Protestants and Muslims.
It was published on Tuesday by LifeSiteNews, a conservative Catholic website that often is a platform for attacks on the pope. Last year, it ran a document by the Vatican's former ambassador to Washington, Archbishop Carlo Maria Vigano, calling on the pope to resign.
A Vatican spokesman had no comment on the letter, which includes dozens of footnotes, Bible verses, pronouncements by previous popes, and a separate bibliography. The letter invites people to join an on-line signature drive.
Addressing the bishops, the letter says "We therefore request that your Lordships urgently address the situation of Pope Francis's public adherence to heresy."
It asks them to "publicly to admonish Pope Francis to abjure the heresies that he has professed".
A significant part of the letter concentrates on "Amoris Laetitia" (The Joy of Love), a 2016 papal document that is a cornerstone of Francis' attempt to make the 1.3 billion-member Church more inclusive and less condemning.
In it, Francis called for a Church that is less strict and more compassionate towards any "imperfect" members, such as those who divorced and later remarry in civil ceremonies.
Under Church law they cannot receive communion unless they abstain from sex with their new partner, because their first marriage is still valid in the eyes of the Church, unless they have received an annulment. The Church does not allow divorce.
Francis has opened the door to some exceptions, allowing the decision whether the person can be fully re-integrated and receive communion to be made by a priest or bishop jointly with the individual on a case-by-case basis.
After Amoris Laetitia was published, four conservative publicly challenged the pope, accusing him of sowing confusion on important moral issues. He has thus far not responded to their demands that he clear up their doubts.
The new letter lists pages of what it calls "Evidence for Pope Francis being guilty of the delict (crime) of heresy".
It attacks him for having once said that the intentions of Martin Luther, the father of the Protestant Reformation, "were not mistaken". It says he has not condemned abortion strongly enough and is too lenient with homosexual Catholics.
The letter criticised Francis for signing a joint statement with Lutherans in 2016 in which the pope said Catholics were grateful for the "theological gifts" of the Reformation.
It also attacked the pope for a common statement with a prominent Muslim leader in Abu Dhabi in February which said that the pluralism and diversity of religions was "willed by God". Conservatives say the Roman Catholic Church is the only true one and that members are called to covert others to it.
The letter launches personal attacks on 22 people, nearly all of them current or past Church figures, asserting that their association with the pope supports their accusation of heresy.