Pope Francis on Tuesday called for church unity during one of the most polarised periods in modern Catholic history, as he marked the 60th anniversary of the Second Vatican Council.
Known as Vatican II, the council sat between 1962 and 1965, opened by Pope John XXIII and closed by Pope Paul VI. Delegates from around the world modernised the ancient Church, producing 16 documents that affected many aspects of Church life.
Council fathers, as they were known, introduced a new liturgy in local languages to largely replace the old Latin Mass and opened the Church to dialogue with other religions.
One document repudiated the concept of collective Jewish guilt for Jesus' death, revolutionising Catholic-Jewish relations after nearly two millennia of mistrust.
But in recent decades some of the Council's teachings have become the subject of deep controversy, particularly in rich countries, where divisions often fall along political lines.
In the homily of a Mass in St. Peter's Basilica - where a glass casket holding the body of Pope John XXIII was brought closer to the altar for the occasion - Francis said both sides were at fault.
"Both the 'progressivism' that lines up behind the world and the 'traditionalism' and 'moving backwards' that longs for a bygone world are not evidence of love, but of infidelity," he said.
He decried "quarrels, gossip and disputes," over Council reforms, saying they were here to stay and that people should "live their faith with joy, without grumbling and criticising".
Both former Pope Benedict and Pope John Paul II had relaxed restrictions on the Latin Mass in an olive branch to conservatives.
But Francis reintroduced them last year, saying his predecessors' leniency, while well-intentioned, was being "exploited" for ideological reasons.
Religious conservatives in the United States in particular have used the Latin Mass debate to align with politically conservative media outlets to criticise the pope over a host of other issues such as climate change, immigration and social justice.
In his homily, Francis said Catholics should not "prefer to cheer on their own party" but be servants of all. They should want to be known as brothers and sisters rather than progressives or conservatives, he said.
(Reporting by Philip Pullella; Editing by David Gregorio)