The Catholic Church risks a schism if it elects another liberal leader like Pope Francis, a leading conservative cardinal has warned ahead of next month’s conclave.

Gerhard Müller also cautioned cardinals arriving for the papal vote to avoid the backroom manoeuvres depicted in the Oscar-winning film Conclave.

“It’s not a power game played by stupid people looking to manipulate, like in this film, which has nothing to do with reality,” the German cardinal said.

Müller, 77, has long been a leading light among Catholic conservatives who opposed the “mercy before dogma” approach of Francis, who died on Monday.

Appointed by Francis’s traditionalist predecessor Benedict XVI as the Vatican’s doctrinal chief, Müller kept his job after the Argentinian pontiff’s election in 2013 but soon challenged his leader’s liberal agenda.

In 2017 he was dropped by Francis after criticising the pope’s decision to allow communion for divorcees who remarry outside the church. His views will now carry weight with conservative cardinals determined to elect a doctrinaire successor to Francis.Nearly 80 per cent of the 135 cardinals eligible to vote may have been picked by Francis, pointing to a potential liberal majority, but the views of many will not be known until they mingle with fellow cardinals at the pre-conclave meetings known as general congregations.• Who will be the next pope? The candidates who could succeed FrancisAsked if he would promote his brand of doctrinal Catholicism at those meetings, which begin in earnest after Francis’s funeral on Saturday, Müller said: “I have to do it; I owe it to my conscience.”The alternative, he said, was a Church that risks splitting in two if an “orthodox” pope is not elected.“No Catholic is obliged to obey doctrine that is wrong,” he said, adding: “Catholicism is not about blindly obeying the Pope without respecting holy scriptures, tradition and the doctrine of the Church.”Speaking in his book-lined apartment yards from the Vatican, Müller listed his differences with Francis, starting with the late Pope’s 2023 decision to allow the blessing of same-sex couples, reversing a ban. Francis said at the time “we cannot be judges who only deny, push back, exclude”, but the move sparked a rebellion, with bishops in Africa and Asia refusing to permit the blessings.The Vatican claimed the move did not imply the approval of gay marriage or gay sex but Müller claimed “it was obviously against Church doctrine”, adding: “God instituted the matrimony of one man and one woman and we cannot change that.”Müller has listed his differences with Francis, starting with the late Pope’s 2023 decision to allow the blessing of same-sex couplesANDREW MEDICHINI/APThe cardinal also took issue with Francis’s talk of the “brotherhood” between Catholics and Muslims, arguing that “Catholics are brothers and sisters in Christ”.Müller is one of a handful of leading conservative thinkers in the Catholic Church based in Rome, alongside the American cardinal Raymond Burke. A former bishop of Regensburg in Germany, Müller has also been the head of dogmatic theology at Munich’s Ludwig Maximilian University.In a 2023 book that will be a convenient manual for conservatives at the conclave, Müller criticised Francis’s deal with China to jointly appoint bishops, likening it to Vatican appeasement of the Nazis in the 1930s and warning: “You cannot strike deals with the devil.”Müller described Francis as a “good man”, but the list of grievances with his papacy extended to a focus on caring for migrants and the environment. The next pope, Müller argued, should not “look for the applause of the secular world that sees the Church as a humanitarian organisation doing social work”.Looking ahead to the general congregations, he said: “I hope these things will be spoken about, and I hope cardinals are not so influenced by what they are reading in the headlines.”• Why Pope Francis’s deal with China may define his legacyHe added that “Pope Francis is well viewed by the mass media and there is a risk [the cardinals] are saying, ‘We should continue’ .” Instead, he said, “they have the responsibility to elect a man who is able to unify the Church in the revealed truth”.Müller shrugged off the labels “liberal” and “conservative”, pointing out the divide in the Church was deeper. The pope, he said, “must be orthodox — neither a liberal nor a conservative”.He said that “the question is not between conservatives and liberals but between orthodoxy and heresy”, adding: “I am praying that the Holy Spirit will illuminate the cardinals, because a heretic pope who changes every day depending on what the mass media is saying would be catastrophic.”Müller also took issue with crowd-pleasing popes who hug and kiss babies — a reference to Francis, who did just that during his final popemobile ride in St Peter’s Square on Sunday. “Not everybody wants to be kissed by old men,” he said with a smile.