Cardinals Gerhard Müller and Robert Sarah encouraged unity over partisanship at a conference held in Rome Thursday to mark the 10th anniversary of Benedict XVI's motu proprio on the "extraordinary form" of the Roman liturgy.

"We must also overcome the tensions and polarizations," Cardinal Gerhard Mueller, prefect emeritus of the Congregation for the Doctrine of the Faith, told CNA Sept. 14 . He noted that some in the Church say "we belong to this party," while others say "we belong to that party."

"That is not Catholic," he said, and stressed the need to understand the liturgy "in the context (of) and with a deep understanding of the fundamentals; what is the essence, what is the substance of the liturgy?"

Cardinal Müller was a keynote speaker at the Fifth Roman Colloquium on Summorum Pontificum, which was held in thanksgiving for the 10th anniversary of the motu proprio.

Other keynote speakers at the event included Archbishop Guido Pozzo, Secretary of the Pontifical Commission Ecclesia Dei, and Cardinal Robert Sarah, Prefect of the Congregation for Divine Worship and the Discipline of the Sacraments.

Summorum Pontificum widened access to use of the older form, or "Tridentine" liturgy. It established that the post-Vatican II Roman Missal, first issued by Blessed Paul VI, is the ordinary form of the Roman Rite, and that the prior version, last issued by St. John XXIII in 1962, the "Tridentine Mass," is the Roman Rite's "extraordinary form."

In the motu proprio, Benedict noted that the "extraordinary form" of the Mass was never abrogated. He acknowledged the right of all priests of the Roman Rite to say Mass using the Roman Missal of 1962, and established that parish priests should be willing say the extraordinary form for groups of the faithful who request it.

By publishing the motu proprio, Benedict XVI "wanted to overcome the tensions which came out of the reform of the liturgy" following the Second Vatican Council, Cardinal Müller said.

The main objective of the reform, he said, was "not a change of the fundamentals of the liturgy as an objective praise of God."

"The liturgy we have now is the same substance, the same liturgy, as in the older form, the extraordinary form," he said, reiterating that "the substance, the constitutive elements, are the same."

Cardinal Müller said the Church must look to the new rite "altogether, in this new synthesis," rather than falling into division.

Liturgy, he said, "is a participation in the work of salvation, it is a participation of the life of...Jesus Christ …  and in the Holy Spirit, who is present in all life and all the sacramental actions of the Catholic Church."

During his address, Cardinal Sarah also emphasized the importance of avoiding division in the Church and focusing on unity, and opened by saying, "God wants the unity of His Church, for which we pray in every Eucharistic celebration."

With Summorum Pontificum, Benedict XVI "wanted to establish a sign of reconciliation in the Church, one that has brought much fruit," he said.

"We are called to continue to pursue this path of reconciliation and unity, as an ever-living witness of Christ in today's world."

Cardinal Sarah's address focused on silence and the primacy of God in the liturgy. He stated that "silence of heart, mind and soul" are the key to achieving "full, conscious and actual participation" in the liturgy, which was the very goal of the liturgical movement.

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Pointing to the "scandal of the divisions" in the Church following the liturgical reform following the Second Vatican Council, Cardinal Sarah said Summorum Pontificum has done a lot to mend these divisions, but noted that there is also "more to do to achieve the reconciliation Pope Benedict XVI so desired, and which work Pope Francis has continued."

"We must pray and work so to achieve that reconciliation for the good of souls, for the good of the Church and so that our Christian witness and mission to the world may be ever stronger."

The extraordinary form ought to be seen as "a normal part of the life of the Church of the twenty-first century," he said. And while statistically the number of people who attend the older form might, as predicted by Benedict XVI, stay a minority, "there should be no competition between the more recent rites and the older ones of the one Roman rite."

"Both should be a natural element of the life of the Church in our times," he said, adding that "Christ calls us to unity, not division! We are brothers and sisters in the same faith no matter which form of the Roman rite we celebrate!"

Offering a "paternal word" to all those attached to the traditional rite, Cardinal Sarah noted that many people refer to them as "traditionalists," and that even those who attend Masses in the old rite refer to themselves as such, "or hyphenate yourselves in a similar way."

"Please do this no longer," he said. "You do not belong in a box on the shelf or in a museum of curiosities. You are not traditionalists: you are Catholics of the Roman Rite as am I and as is the Holy Father."

As members of the Catholic Church, those who are drawn to the extraordinary form of the Mass "are called by God, as is every baptized person, to take your full place in the life and mission of the Church in the world of today, not to be shut up in – or worse, to retreat into – a ghetto in which defensiveness and introspection reign and stifle the Christian witness and mission to the world you too are called to give."

If experiencing 10 years of Summorum Pontificum has meant anything, "it means this," he said, and told his audience that "if you have not yet left behind the shackles of the 'traditionalist ghetto,' please do so today. Almighty God calls you to do this."