When Pope Francis was elected nearly four years ago, on 13 March 2013, he was escorted – like every pope before him – from the Sistine Chapel to the Room of Tears. It is the place where a new pope pauses for a moment – and no doubt many of them do shed a few tears, thinking of the momentous responsibility upon their shoulders – before stepping out on to the balcony of St Peter’s to greet the world as the new leader of the Roman Catholic church.

When Francis, known until then as Jorge Bergoglio, archbishop of Buenos Aires, first appeared that night, he appeared remarkably sanguine, joking that the cardinals had gone to the ends of the Earth to choose the next pope. If he’d had any inkling of what these last four years would be like, he would surely have wept in that Room of Tears.

While hugely popular across the globe with Catholics and non-Catholics alike, Francis has struggled against fierce opposition from the Vatican establishment to haul the Roman Catholic church into the 21st century, fought to reform its government, tried to persuade cardinals to revise their thinking on the divorced and remarried, and been openly opposed by rebel prelates.

Last week marked the start of Lent, one of the most important periods of the church’s calendar, a time when Catholics fast, give alms and reflect on humanity’s sinfulness in the run-up to their commemoration of the crucifixion and of Easter. It is usually marked by quiet prayerfulness, and on Sunday the pope, along with members of the Roman Curia, will leave Rome to begin a five-day retreat. He will leave a Vatican beset by tension, turmoil and rebellion. There are even rumours that growing numbers of Vatican hands think he should quit.

On Ash Wednesday, the first day of Lent, came a big blow, in effect caused by the pope’s enemies: Marie Collins, the last abuse survivor on his commission into child abuse in the church, quit, frustrated at the lack of progress and what she calls “shameful lack of cooperation” from the officials most concerned with cases of abuse, highlighting the intransigence of the Roman Curia, or governing body, in the Vatican – the body Pope Francis wants to reform.

With Collins gone from the Commission for the Protection of Minors, set up by the pope to investigate the worldwide scandal of sexual abuse by priests and religious brothers, and the other victim representative, the Briton Peter Saunders, on indefinite leave of absence, the commission has lost a certain integrity.

When she stepped down, Collins complained that the commission had been starved of resources, progress was slow and there was “cultural resistance” to its work in the Vatican.

The commission’s recommendation that there should be a tribunal set up to deal with bishops who had been negligent over abuse has been impeded by Roman Curia officials despite the pope himself approving it. “There is an area of the Curia that has not moved into the 21st century,” said Collins. “It is very resistant to working with the commission. There are people who still want to cover up.”

Pope Francis leads the Ash Wednesday procession and mass at Santa Sabina church in Rome. Photograph: Alessandra Benedetti/Getty Images

The opposition Pope Francis is facing puts the church into uncharted territory. Massimo Faggioli, a leading theologian and Vatican-watcher, said: “The Vatican status quo is behind this. It is a cultural and political opposition that was already visible a few weeks after Pope Francis’s election. They are against changing the style and position of the church from a western one to a global religion.”

In Francis’s early days as pope, Vatican whispers focused on the financial reforms he wanted to make. Pope Benedict had resigned after a series of revelations, known as Vatileaks, which exposed financial malpractice in the Vatican, and Francis sought to end it.

But the most vocal opposition to the pope has developed over his desire for debate about marriage and divorce, gay people and the family.

After two synods on the issues in 2014 and 2015, Pope Francis produced the document Amoris Laetitia, in which in effect he told the church’s bishops to make local decisions about the divorced and remarried and their receiving of communion.

Traditional church teaching says that a Catholic who remarries after divorce can receive communion only if the church has also annulled his or her first marriage. Some bishops have seen Amoris Laetitia as a direction to compassionately welcome people without annulments to receive the eucharist.

That has outraged conservatives. A letter to Pope Francis from four cardinals hostile to change was made public. The communication took the form known as a “dubia”, expressing doubts, demanding yes and no answers and in effect challenging the pope’s authority by asking him to make points of church teaching clear on this issue and Christian life.

The four accusers included three retired cardinals, plus Cardinal Raymond Burke, an arch-conservative American canon lawyer who has gone as far as threatening to issue a correction to Pope Francis over Amoris Laetitia. Burke has been a thorn in the pope’s side for some time.

He was given a powerful judicial role in Rome by Benedict XVI, from which Pope Francis moved him. Last year Burke and other conservatives were ousted from the Vatican department that oversees worship. Then, earlier this year, during a row between the pope and the ancient Knights of Malta which led to the departure of the order’s British leader, Matthew Festing, Cardinal Burke was sidelined in his role as envoy to the order. Within days anti-Francis posters appeared on the streets of Rome; so has “fake news” by way of spoof Vatican newspaper pages mocking him.

The rows are not just about personality clashes, or even divorce and communion. It goes much deeper than that. This is about the future of the church. If previous popes had enacted the wishes of the modernising Second Vatican Council, held 50 years ago, the domination of the wider church by the Vatican would have already diminished.

Now Francis is trying to move at least some decisions out to the bishops and local churches across the globe, by allowing priests and bishops to make the decisions about allowing divorcees communion. That, for the traditionalists, is the thin end of the wedge.

Christopher Lamb, Rome correspondent of the Catholic weekly the Tablet, said: “The fundamental shift that Pope Francis is trying to make is for the church to be more pastoral. The Roman Curia should be serving the church universally, but Marie Collins in her resignation has exposed what is going on: a department has not even been willing to answer letters from abuse victims.”

According to Tina Beattie, a British feminist theologian who organised “fringe” events in Rome before the 2015 synod to get women’s voices heard, Pope Francis has a “blind spot about women” and hasn’t listened enough to them, but she admires him for attempting to have some dialogue.

“I don’t want to say that the pope is defeated by the critics, but this is making him vulnerable. What they are doing is almost schismatic,” she said.

On Sundaymorning in Rome, the pope will no doubt mark the first Sunday in Lent with a call to repent. But his critics are hardly in penitent mood; they want him to resign. There are rumours that even some of those who voted for Francis now have doubts.

“It is true that some cardinals may regret their vote for him in the conclave, but I do not think they hope that he resigns,” said Faggioli. “They know it would be very hard to find a popular pope like him.”

FLASHPOINTS: HOW CONSERVATIVES HAVE BEEN UPSET

Homosexuality

On the way home from his first trip abroad to Rio de Janeiro in July 2013, Francis told journalists that he did not have a problem with an inclination to homosexuality. “Who am I to judge if they’re seeking the Lord in good faith?” he said.

Communion for divorced and remarried people

In April 2016 the pope issued his apostolic exhortation in response to the two synods of 2014 and 2015 on marriage and the family. Footnote 351 indicated it might be possible for the divorced and remarried to receive communion and moved decisions on this to local bishops and priests. “Communion is not a prize for the perfect,” he said. Six months later, four of his fiercest critics, including Cardinal Raymond Burke, issued a “dubia”, a document challenging Francis over his thinking on communion.

Cleaning up the Curia

After being elected on a reform mandate by the College of Cardinals in March 2013, Francis immediately started his reform of the Roman Curia, the church’s bureaucracy, with efforts to clean up finances and streamline departments. In December 2016, Francis accused the leaders of the Curia of malicious and hidden resistance to reform, a resistance that was a sport that “sprouts in disturbed minds”.

Child protection and the sex abuse scandal

Pope Francis created a Commission for the Protection of Minors, under his close ally, Cardinal Seán O’Malley of Boston. In June 2015 the commission proposed a tribunal that would hold bishops to account for failing to deal with reported cases of child sex abuse. Francis gave it his backing, but the Congregation for the Doctrine of the Faith found it had unspecified legal problems. The commission has stalled ever since.

Luther had a point

Francis went to Sweden in October 2016 to mark the quincentenary of the Reformation. During a service in Lund Cathedral he praised Martin Luther for restoring the centrality of scripture. “There was corruption in the church, worldiness, attachment to money and power,” he said. Some conservatives were unimpressed by this display of ecumenism.