(AINA) -- In early December, Patriarch Awa spoke on the possible reunification of the Assyrian and Chaldean Churches, expressing opposition to any form of "uniatism" in the process. Patriarch Sako responded first on December 31 and then more fully on February 28. In his latter response, Patriarch Sako called for an integrated strategy moving forward that:

• overcomes prejudices in favor of renewal, deep study, and clear agreement,
• builds upon shared ecclesial identity rather than nationalism,
• includes asking forgiveness for the mistakes of the past,
• avoids the absorption of the believes of one particular church into another,
• draws Assyrians and Chaldeans together into one patriarchate through a synodal style and practice,
• restores Eucharistic communion among all the apostolic Churches, and
• preserves the dignity of each patriarchal Church.

In a recent article, I also responded to the comments of Patriarch Awa and, in line with his concern with "uniatism," criticized the code of canon law common to the Eastern Catholic Churches (CCOE). However, as Patriarch Sako made clear on February 28, dialogue between Assyrians and Chaldeans must attend to the strengths of the Chaldean Church as well, such as her authentic customary practice and Chaldean particular law.

In this article, I would like to examine an aspect of Patriarch Sako's earlier reply of December 31. There he did not only respond to Patriarch Awa's comments. He also defended the unity in faith shared by all the apostolic churches -- Assyrian, Miaphysite, Orthodox, and Catholic -- and distinguished between obstacles to unity that are doctrinal, on the one hand, and obstacles to unity that are ecclesiastical or canonical, pertaining to authority and leadership, on the other hand. Equipped with this helpful distinction, in what follows, I will review and comment on the set of potential obstacles to the reunion of Assyrians and Chaldeans.

We'll begin with questions of doctrine, since unity in faith is the most fundamental dimension of Christian unity. In agreement with most Catholics, Patriarch Sako has clearly expressed his view that all the apostolic Churches profess one and the same Christian faith, though they employ different linguistic expressions to do so. Unfortunately, Catholics are often accused of having distorted the apostolic faith through innovative doctrines. Eastern Christians and Western Christians have many different practices and traditions, but the list of potential doctrinal innovations dividing Catholics and non-Catholic Eastern Christians is quite short.

The first question of doctrine concerns Christology. From the 5th century, differences in Christology divided the Church of the East, the Miaphysite Churches, and the Latin and Byzantine Churches into separate communions. In the last few decades, however, Rome has mutually recognized with the Miaphysite Churches and mutually with the Assyrian Church of the East the orthodoxy of their Christological traditions as well. From both the Catholic and Assyrian perspectives, Christology on its own presents no obstacle to communion among all the apostolic Churches. Yet there are perhaps two further complications.

First, the Orthodox and the Miaphysite Churches do not recognize the orthodoxy of the anti-theopaschite Christology of St. Babai the Great and will need to examine this Christological tradition while abstracting from practical questions about the reception of ecumenical councils and the consequences of historical anathemas. Second, I expect that the Assyrian Church will likely scrutinize Chaldean liturgical and catechetical materials for any potential departures from the Christology of St. Babai the Great. This will inform the efforts of Assyrians and Chaldeans to harmonize their liturgical and catechetical practices in the reunited Church of the East.

Next come two significant doctrinal controversies of the Middle Ages: concerning Purgatory and the Filioque clause. The Catholic doctrine of Purgatory refers to a temporary condition of suffering by the elect after death in preparation for Heaven. This doctrine generates controversy in both East and West. Its historical abuse, through the monetization of indulgences, drove the Protestant Reformation. It also assumes a concept of Christian perfection that doesn't resonate with Protestant thought. The doctrine once offended the Orthodox because it seemed to refer to a physical location. Although this issue has been clarified, the doctrine can still offend because it seems to confuse a suffering that is purgative, transformative, and therefore in many cases necessary for an individual on the way to life in Heaven with a suffering that is expiatory, remittable, and therefore not necessary for an individual on the way to life in Heaven.

The Filioque clause refers to the addition of the phrase "and the Son" by the Latin Church to the Nicene-Constantinopolitan Creed, so that it reads, "I believe in the Holy Spirit...who proceeds from the Father and the Son." The clause offends the Orthodox because it seems to subordinate the Holy Spirit to the Son and to obscure the monarchy of the Father, i.e. the uniqueness of the Father as the source of the Blessed Trinity. The addition was originally intended to emphasize the divinity of the Son, was later used to distinguish the generation of the Son from the spiration of the Holy Spirit, was for a time resisted by Rome, and was finally admitted to the Roman liturgy in 1014 after having exhibited in the judgment of Rome no threat to orthodox Christianity for centuries. The Catholic Church today acknowledges the authority of the original creed but also defends the orthodoxy of the phrase.

At the time of the Union of Brest in 1595, the Eastern Christians restoring communion with Rome were not expected to adopt these two controversial doctrines as their own. They retained their own traditions, rite, and calendar but acknowledged the validity of Western sacraments and a universal ecclesiastical authority in the Roman Pontiff. Unfortunately, further schism followed, and Byzantine tradition suffered. Despite the subsequent phenomena of "uniatism," the Union of Brest still represents one possible position with regard to the issues of Purgatory and the Filioque: As doctrines in the West, they need not be adopted in the East, and they represent no obstacle to communion.

This approach does not likely satisfy the Orthodox at present. Perhaps further clarification by the international dialogue commissions will. Otherwise, the Catholic Church may need to develop her positions in a manner acceptable to the East. For example, the Catholic Church could someday distinguish between two dimensions of suffering in Purgatory: Just as, by punishment, human justice both disciplines the guilty and restores the community, so too might we understand the suffering of Purgatory both to purify the dead and to edify the living. The Church could not remit the suffering that is strictly necessary for the dead to prepare for Heaven. But she could remit the suffering that edifies the living, because the living may be edified by other means. It seems that for this very reason the Church invites the living to redeem by prayer and good works some measure of suffering assigned to the dead.

Regarding the Filioque, the Catholic Church cannot simply excise the phrase without significant risk of schism, but perhaps it can be replaced. By the Greek word ekporeuesthai (John 15:26), Scripture supports the Orthodox argument that the Holy Spirit proceeds from Father alone, according to Its manner of origin. Scripture also presents the Holy Spirit as a paternal blessing of the Father upon the Son (Cf. Matthew 3:16-17, Mark 1:10, Luke 3:22). The image of the Holy Spirit as a paternal blessing of the Father upon the Son could serve both to emphasize the monarchy of the Father and to distinguish the processions of the Son and the Holy Spirit, because it assumes the (non-temporally) prior generation of the Son. So maybe, just maybe, the West could someday confess with the approval of the East that the Holy Spirit "proceeds from the Father like a blessing upon the Son" (ex Patre sicut benedictus super Filium procedit).

Four more doctrines, promulgated in modern times, cause controversy with the East. While every controversy of doctrine also involves some controversy over ecclesiastical authority, this is especially true of these four. The first is papal primacy. In some way, the doctrine is already shared between East and West. All the apostolic Churches consider Rome the first see and acknowledge that this position entails certain prerogatives. They disagree regarding how Roman primacy is exercised within the Catholic Church today and over how strongly it was defined by the First Vatican Council.

In recent decades, the popes have suggested that the Catholic Church can certainly adapt the exercise of papal primacy in light of ecumenical concerns. (I take these suggestions to be genuine and see little value or Christian virtue in viewing them with suspicion.) In 1995, St. John Paul II invited non-Catholics to "patient and fraternal dialogue" "to find a way of exercising the primacy which [is] open to a new situation" (Ut Unum Sint §§95-96). Likewise, during his visit to Istanbul in 2014, Pope Francis said, "To reach the desired goal of full unity, the Catholic Church does not intend to impose any condition except that of the shared profession of faith." Yet, this flexibility has not resolved the controversy. Patriarch Awa, for example, has objected insofar as the shared profession of faith includes the doctrine of the ordinary jurisdiction of the Roman Pontiff over all the Churches and all the faithful.

Hopefully, the Joint International Commission for Theological Dialogue between the Catholic Church and the Orthodox Church will soon produce for consideration by all the apostolic Churches a document -- "Primacy and Synodality in the Second Millennium and Today" -- with language that better illuminates the shared faith of East and West. We may glimpse some of this language in a letter of February 20, 2019 from Ecumenical Patriarch Bartholomew to Archbishop Anastasios of Tirana:

Accordingly, not only in cases of Doctrine, holy Tradition, and Canonical Church Regulations, or even of general matters concerning the entire body of the Church, but also in all matters pertaining to important issues of specific interest to one or another Local Church, the supervisory provision and protection of the Great Church of Christ intervenes -- sometimes ex officio and out of obligation, at other times at the request of interested parties -- in order to offer an effective contribution for the sake of arbitration and resolution of differences arising among the holy Churches of God, to settle differences between shepherds and their flocks, to avoid inflaming difficulties and facilitate the return of Ecclesiastical affairs to a Canonical path, to bolster the occasional inadequate ministry of spiritual leaders in certain Churches, to support the weak, wavering, or misled in the Orthodox faith, and overall never to delay or eschew suppressing all kinds of moral and material danger that threatens the stability of the most holy Churches.

The next controversial doctrine, also promulgated by Vatican I, is papal infallibility. This doctrine can be derived from an ancient belief that Catholics understand to have been universally held throughout the early centuries of Christianity in both East and West: that the faith does not fail in Rome. This is called "Roman indefectibility." From this position, it follows that if the Church of Rome receives a doctrine concerning faith or morals promulgated in the most formal manner (ex cathedra) by the Roman Pontiff -- i.e. if the Church of Rome remains in communion with him, so that he remains the Roman Pontiff -- then the doctrine is thereby and without further reception known to be infallible. Unfortunately, papal infallibility has the appearance of an especially obnoxious innovation. But it is simply a logical consequence of the premise of Roman indefectibility. When the validity of the argument is recognized, the debate shifts to its soundness: Did the Church ever in fact universally accept Roman indefectibility?

Only two doctrines are widely defended by Catholics as having been infallibly defined ex cathedra. These are also the two remaining controversial doctrines of the modern period: the Immaculate Conception, that Mary "at the first instant of her conception, by the singular grace and privilege of almighty God and in view of the merits of Jesus Christ...was preserved immune from all stain of Original Sin," and the Assumption, that she, "having completed the course of her earthly life, was assumed body and soul into heavenly glory." Both belong to the shared faith of East and West. Some Orthodox theologians object to the Western concept of original sin employed in the definition of the Immaculate Conception, but the doctrine does not assert a specific concept of original sin, only that Mary was not subject to it. Therefore, the doctrine allows for interpretation acceptable in the East. So the controversy over these doctrines is less about the doctrines themselves than about the ecclesiastical authority to define them.

Because it is a definition of the most formal sort, an ex cathedra statement obligates all Christians to receive the doctrine defined. On the one hand, this may offend non-Catholics as presumptuous. On the other hand, this places papal infallibility and Roman indefectibility at the service of the Universal Church and limits the use of ex cathedra statements to only those doctrines whose further definition is worth any risk of subsequent schism. In relation to non-Catholic Christians who seek to restore communion with Rome, it is unclear to what extent Rome would expect them to receive ex cathedra statements and other doctrinal developments promulgated during the time of schism. In fact, even in communion, the question of whether a doctrine has been adequately received is perhaps always one of pastoral prudence.

On one extreme, Rome could expect from the Eastern Churches no more than the recognition that she maintains like them one and the same Christian faith. But if the East comes simply to tolerate the doctrinal developments in the West as pious legends, in time these will again come to appear to the East as distortions of the faith, and schism will follow. On the other extreme, Rome could expect the Eastern Churches to adopt all the doctrinal developments in the West as their own, just as they are proposed by Rome's extraordinary and ordinary magisterium. But this undermines the diversity and integrity of the Eastern Churches and their traditions. In fact, both Orthodox and Eastern Catholic theologians have pushed back against Catholic theories of an organic or progressive development of doctrine demanding universal assent. (Cf. Andrew Louth's "Is Development of Doctrine a Valid Category for Orthodox Theology?" and Joel Barstad's "Are the Ratzinger Proposal and Zoghby Initiative Dead?")

It is perhaps sufficient for the restoration of communion with Rome if the international ecumenical dialogues uncover in the Eastern traditions basic concepts of papal jurisdiction and Roman indefectibility. These concepts might then serve as common ground for regulating East-West relations and as protection against accusations of heresy for their further development in Western tradition.

Returning to Patriarch Sako's distinction between doctrinal issues, on the one hand, and ecclesiastical issues, on the other, we have just reviewed all the potential doctrinal divergences that have caused commentators to doubt whether the apostolic Churches share one and the same Christian faith. Again, most Catholics see one and the same faith expressed differently among the apostolic Churches, and hope that the ecumenical dialogues will at last make this agreement clear to all.

Beyond issues that strictly concern the faith, there are some that relate simultaneously to doctrine and discipline, such as the enumeration of ecumenical councils. The question of councils is more ecclesiastical than doctrinal because it falls outside the deposit of faith. The ecumenical councils belong to sacred tradition but not to the Gospel itself. For this reason, pastoral prudence can seek a differentiated consensus regarding a common enumeration of ecumenical councils. Maybe all four communions of apostolic churches could someday enumerate together seven or eight councils of the first millennium.

Regarding the councils of the second millennium that Catholics have called "ecumenical," I doubt that the Eastern Churches need receive these as their own, nor need they receive the two ex cathedra statements. Yet, perhaps the Eastern Churches could still recognize these councils and declarations from the West both as orthodox and as protected from error by virtue of Roman indefectibility. Among Eastern Christians, Eastern Catholics may be best positioned to discern what doctrinal resources in the West are most useful or receivable for the Churches of the East. For example, the Council of Trent still helpfully informs ecumenical dialogue with Protestant Christians. The growth of Eastern Catholics in authenticity to the traditions that they share with their non-Catholic counterparts need not entail the abandonment of insights from the West but the further development of these insights according to their own traditions.

The question of canonical consequences of historical anathemas is similar to the question of ecumenical councils. Anathemas against individuals fall outside the deposit of faith. Therefore, as St. Eulogius of Alexandria explicitly argued in the sixth century, past anathemas and the even the commemoration of condemned heretics need not prevent the restoration of communion. Only present agreement in the faith is absolutely necessary. St. Eulogius' lost account of oikonomia is summarized in the 227th opuscule of the Bibliotheca of St. Photius. It will likely become a necessary resource for the Assyrian Church of the East to restore communion with the Orthodox and Miasphysite Churches.

Other issues are almost entirely ecclesiastical. For example, restored communion between East and West will require a whole new body of protocol to govern East-West relations. The Code of Canons for the Eastern Churches (CCOE) which presently governs relations between Rome and the Eastern Catholic Churches will be abrogated, as foreseen by the final section of Orientalium Ecclesiarum, and each Eastern Catholic Church will need to develop a plan for integration with her corresponding non-Catholic Church or jurisdiction. Toward this end, despite the future abrogation of the CCOE, I proposed that the Chaldean Church and other Eastern Catholic Churches take steps to reform the CCOE, removing from it those canons least acceptable to their non-Catholic counterparts.

To govern relations among themselves, many Eastern Churches will likely seek clarification regarding the diptychs, i.e. order of precedence among patriarchs and primates of the Churches. The traditions of both Rome and the Church of the East assign to the Church of the East the sixth position: after Rome, Constantinople, Alexandria, Antioch, and Jerusalem. Assyrians and Chaldeans will have to determine together the location and designation of their patriarchal see, e.g. Baghdad, Seleucia-Ctesiphon, Erbil, Arbela.

The Eastern Churches will also seek clarity regarding canonical territory and their right to care for their faithful in diaspora. Thankfully, every apostolic Church is likely ready to recognize the jurisdiction of the Church of the East in Iraq and Iran. The Churches of Rome, Russia, and India may challenge territorial claims farther east. But the history of the Church of the East throughout Asia is indisputable, and therefore the Churches must find ways to respect her historical presence there. For example, they could recognize a right of the Church of the East someday to accede to and enjoy primacy in the Federation of Asian Bishops' Conferences (FABC) or its future counterpart.

Both among and within Churches, there will be need to harmonize divergent pastoral approaches to failed marriages and irregular unions. In the West, the fathers of Trent declared these divergent practices not church-dividing, and in the papal synods of 2014 and 2015 Pope Francis sought ways to bring these practices closer together. Ultimately, the resulting exhortation Amoris Laetitia did not imitate Eastern practice and remains controversial. In the Christian East, Orthodox theologians have called for pastoral practices that better communicate the indissolubility of marriage, such as requiring penance of those who seek to remarry. Although not yet achieved, harmonization remains possible.

Finally, as Eastern Catholics and their non-Catholic counterparts develop their plans for integration, they will need to consider when it will be pastorally appropriate to allow for sacramental sharing and concelebration and when the time will come for the integration of corresponding hierarchies and jurisdictions. They will need to review together their calendars and martyrologies, liturgical practices and canonical practices, catechetical and theological materials, and spiritual and pastoral practices. This is precisely the integrated strategy for which Patriarch Sako has called. And, in fact, Patriarch Awa calls for the same, just with more pointed emphasis on the heritage of the Church of the East.

It may appear that the obstacles to reunion of Assyrians and Chaldeans within one Church of the East are many and complex. But they are hardly insurmountable. Unity will require hard work and careful planning, pastoral prudence, and openness in the hearts of each of the faithful to the blessings of unity that Christ desires for all His brothers and sisters. Each in his own way, the patriarchs have called upon Assyrians and Chaldeans to envision together their common ecclesial life. As this vision becomes clear, it will become the responsibility of Assyrians and Chaldeans together to cherish it, to defend it against every evil power and extra-ecclesial interest that opposes it, and to see it at last brought to perfection.