The Orthodox Church and Summorum Pontificum

Similarly, it must not be forgotten that from the beginning the Churches of the East have had a treasury from which the Western Church has drawn extensively in liturgical practice, spiritual tradition, and law. - Unitatis Redintegratio

A number of critics have argued that Benedict XVI's motu proprio Summorum Pontificum has created obstacles, as far as ecumenism is concerned. Is this true? Is the Tridentine Mass such a stumbling block? 

In the opinion of Cardinal Burke:  

"I wouldn't think that the Holy Father would be doing this simply as a strategy, but I do think it will be an effect of a restoration or in the 'reform of the reform' of the liturgy. It seems to me for the Eastern rites, and for those of the Orthodox Churches, the reform of the liturgy after the council and the concrete expression is so stripped of the transcendent, of the sacral elements, it is difficult for them to recognize its relationship with their Eucharistic Liturgies. It would be easier for them to see the unity, the oneness in the Eucharistic Sacrifice, by a rite of the Mass, just limiting ourselves now to talking about the Holy Mass, that it was richer in those dimensions — the elements of the transcendent — the symbols of the transcendent element of Christ — Christ in action in the Mass — the unbloody renewal of the Sacrifice of Calvary". 

A few months before the promulgation of Summorum Pontificum, Eastern Orthodoxy's Patriarch Bartholomew I of Constantinople quoted the phrase lex orandi, lex credendi. This was on the occasion of Benedict XVI's visit to Istanbul in 2006. Bartholomew I argued that "in liturgy we are reminded of the need to reach unity in faith as well as in prayer".

An interesting episode occurred in the same period, when the French episcopate (with an open letter to Benedict XVI) urged the Pope not to issue Summorum Pontificum. Hearing this Bartholomew I of Constantinople supported the Pope, denounced the decay of Catholic liturgy and stressed that the Novus Ordo Missae had in fact hampered relations between the Western and the Eastern branches of Christianity.

The Orthodox in fact were disturbed not only by abuses in the post-Vatican II liturgy, but also by approved practices such as female altar servers, Mass 'facing the people' and Communion in the hand. The Tridentine liturgy therefore bodes well ecumenically, because these problematic practices are simply not standard features of the Classical Roman rite. 

Bartholomew I later on declared that with Summorum Pontificum ​​a huge step forward in reconciliation had been made.

It appears therefore that the Pope's intention to make it easier for the laity to have Mass in the Extraordinary Form was also intended to help prepare the reunion of the two great divided branches of Christianity: Catholicism and Orthodoxy. The Orthodox interpreted Summorum Pontificum as evidence of a renewed seriousness in the Roman Catholic Church of lex orandi, lex credendi.

During the pontificate that is in its final days, Pope Benedict XVI tried ceaselessly to teach that the Catholic tradition has not been lost, that it remains to be discovered and lived. How this will all work out, under the soon-to-be-elected Pope, is yet to be seen.