Synod of Diamper was definitely a forceful illegal invasion of Portuguese Missionaries into the affairs of Saint Thomas Christians. The Arch Bishop of Goa had no jurisdiction over Saint Thomas Christians. Without any special mandate from the Roman Pontiff, he forcefully entered the Arch Diocese of Angamaly and convened the Diocesan Synod of Diamper and proclaimed that he reunited the saint Thomas Christians who were living outside the Roman Communion for thousand years, in a matter of few months by the efforts of the zealous Arch Bishop and his team of missionaries to triumph in Europe. (Jonas Thaliath, The synod of Diamper, Orientalia Christiana Analecta 152 Rome 1958, cited by Rev Dr Paul Pallathu, Was Saith Thomas Christians nestorians ? Ephrem’s theological Journal, vol 5 March 2001, p 36)
It is clear that Saint Thomas Christians were not in explicit communion with the Church of Rome for centuries. But there are certain hints in the history about some loose contacts and communion. Church of the East had several short lived communions and relations with the Church of Rome in the past before the formation of the Chaldean Patriarchate.
Pope Saint Gregory III ( 731-741) was a Chaldean from the province of Syria. ( Guriel Elementa Linguae Chaldaicae, 168 cited by G T Mackenzie in foot note 116 based on the manuscript submitted by Nidheerickal Mani Kathanaar). Mar John, the Arch Bishop of the Syrians and afterwards Patriarch, went with his suffragans to Rome and received the pallium from Pope Callixtus II( AD 1119-1124) in the twelfth century. (Gesta Callixti , Papae. Vetera analecta Mabilloni 468 cited by G T Mackenzie foot note 116 based on the manuscript submitted by Nidheerickal Mani Kathanaar) . In AD 1250, Iso yahb bar Malkon, Metropolitan of Nisbis, sent a profession of Catholic faith to Pope and made some minor changes in the Taksa that he used calling Mary, the ‘Mother of Christ, who is our God’ (History of Chaldean mass, Macomber, JAAS p76). When Pope Julius III, on April 6th, 1553 confirmed John Simon Sulaqa as Patriarch of the Chaldeans, confirmed that the discipline and liturgy of the Chaldeans had already been approved by his predecessors, Nicholas I ( AD 858-867) and Leo X ( AD 1513-1521) and Clement VII, ( AD 1523-1534) This papal letter also mentions the former Patriarch Simon Mamma, of good memory as Patriarch of the Christians of Malabar.( GT MacKenzie, foot note 116)
There are reports in the history about reception of John Marignolli in AD 1346, letter of Pope Eugine IV to the Christian King of Malabar in AD 1439, as examples of contact with the Church of Rome. But after AD 1554, with the arrival of Mar Joseph, The Saint Thomas Christians became in Catholic Communion.
In AD 1551, under the leadership of Patriarch John Simon Sulaqa, a section of the Church of the East entered into full hierarchical communion with the Church of Rome. John Simon Sulaqa was consecrated and confirmed as the Catholic Patriarch of Mossul in Assyria and received pallium from Pope Julius III in AD 1553.In the Papal Bull, the Pope had confirmed his jurisdiction over Malabar Christians also.
. (“..Postmodum vero ecclesia patriarchali de Muzal et insulae Tigris ac caeterarum civitatum et terratum orientalium eidem Patriarchae subjectarum, necnon monasteriorum ejusdem in Sui Massin et et Calicuth ac tota India existentium eidem etiam Patriarchae subditorum dum vivert praesidebat….”S Giamil, Genuinae Relationes… 17-18, Subsidium ad Bullarium Patronatus Portugalliae, 4 cited by Rev Dr Paul pallath, Were Saint Thomas Christians Nestorians ? Ephrem’s Theological Journal, Vol 5 March 2001 No 1 p 42 foot note 24)
The Patriarchate was supported by a Papal Nuncio for the East, Bishop Ambrose Buttigeg, a Maltese Dominican and his companion Fr Antonius Sahara.
Patriarch Sulaqa was murdered in AD 1555 and Mar Abdisho was consecrated as the next Patriarch under the supervision of the Papal Nuncio, Bishop Ambrose Buttigeg. In 1562, Mar Abdisho received pallium from Pope Pius IV. The next Patriarch was Mar Yahballaha ( AD 1567- 1579) and then Mar Simon Denha ( AD 1579- 1600). Mar Simon Denha received pallium from Pope Gregory III (1572-1585). It was this Mar Simon Denha was the head of Saint Thomas Christians who was in explicit ecclesiastical and hierarchical communion with the Church of Rome was condemned by the Synod of Diamper!
Thus, the synod itself become an act of disobedience to the Roman Pontiff.
In AD 1555, Patriarch Mar Abdisho sent two Bishops to Malabar, Mar Joseph Sulaqa, the brother of Patriarch John Simon Sulaqa, as the Bishop for Saint Thomas Christians, Mar Elias, as the representative of the Chaldean Catholic Patriarchate along with the Papal Nuncio for the East Bishop Ambrosius Buttigeg, and his companion Fr Antonius Sahara. This four member team itself proves the authenticity of Mar Joseph and his hierarchical communion with the Roman Pontiff. ( The two Chaldean Bishops were arrested and detained in the Franciscan monastery at Bassein near Bombay and Bishop Abrosius and Fr Sahara were allowed to come to Goa.)
In 1558, all were allowed to come to Malabar because of the arrival of Mar Abraham, another East Syrian Bishop but not of the Catholic communion. They used Mar Joseph to keep the Malabar Nasranis away from the Non catholic East Syriac Church. Mar Joseph converted Mar Abraham to Catholic communion, but the Portuguese deported him to Babylon. Mar Joseph was arrested again in 1562 and sent to Portugal and Rome where he was cleared from all accusations and was even nominated to be elevated as a Cardinal.
Due to the request of the Malabar Nasranis, the Patriarch Abdisho appointed Mar Abraham as the Bishop of Malabar and sent to Rome where he received pallium from Pope Pius IV in 1565.The Pope Pius IV gave him three letters, one for the Patriarch Abdisho and the others to the Arch Bishop of Goa and the Bishop of Cochin.
In these letters, the Pope confirms the jurisdiction of the Chaldean Patriarch over the Saint Thomas Christians and apologised for the inconveniences caused by the Portuguese Missionaries. The Pope also warns the Arch Bishop of Goa that it would be detrimental to the Pope himself and to the Apostolic See, if he would hinder the jurisdiction of the Patriarch and orders that his jurisdiction must remain untouched and intact. The Pope in his letter to the Patriarch permits to maintain ‘your customs and rites’, recognizing the ancient rite.
Thus, the Arch Bishop of Goa, who had no jurisdiction over the saint Thomas Christians, without any special mandate from the Roman Pontiff, forcefully entered the Arch Diocese of Angamali with the help of the non Christian Kings invalidly convoked the diocesan Synod of Diamper, under the threat of excommunication contrary to the norms of the canon law.( Rev. Dr.Paul Pallathu, The Synod of Diamper valid or invalid, cited in Were Saint Thomas Christians Nestorians ? Ephrem’s Theological Journal, Vol 5 March 2001 No 1,p 54-55) The word excommunication is also to be noted carefully. If saint Thomas Christians were not in communion with the Catholic Church, how can the Arch Bishop Goa excommunicate them? They would not have afraid of excommunication and the threat of excommunication would not have any use.
What was the aim of the synod ?
It was not for correcting the doctrines of saint Thomas Christians. The above mentioned letters categorically confirms that the rite and rituals of Saint Thomas Christians were accepted by the Roman Pontiff. If for argument sake, if we take that there were several books found in the community which contains errors, the synod would have only made actions to correct them. Instead, it was a strategical approach to make changes to the rite and customs to conform the saint Thomas Christians to latin rite to effect suppression of law of Thomas- and to introduce Latin Rite among saint Thomas Christians. See below a few of the synodal decrees which explicitly order conformity to Latin rite.
‘admit and receive all the customs rites and ceremonies recieved and approved in the Roman Church’ Session II decree I.Images painted after ‘our manner’ are to be placed in all churches…session III decree I Ch IX.The Syriac lectionary is to be replaced by The Vulgar latin edition made use by Holy Mother Church-Session III decree II.prohibition of the east Syrian baptismal formula and prescribed that which is followed by the Roman Church- session IV decree I.baptismal water shall be blessed by the Holy chrism according to the Roman ceremonial-session IV decree XIX.separated confirmation from baptism in harmony with the roman tradition- session IV confirmation.Forty changes in the eucharistic liturgy to conform with the latin rite-words of consecration was added to the Liturgy of Addai and mari, creed was modified, introduction of extreme unction, abolished optional celebacy to obligatory celebacy to the priests, latin vestments, the synod being desirous that the church of the serra should in all things be conformable to the latin customs, or Holy Mother Church of Rome….’session VIII decree XXXVII.
From these, we can understand that the real aim was not the correction of errors but to eradicate and exteminate the east Syriac rite and Law of Thomas to replace it with latin Rite.
2 To suppress the Jurisdiction of the Chaldean Patriarch and to bring the Saint Thomas Christians under the Portuguese Padruado and patronage of the King of Portugal to control the Saint Thomas Chriastian community and thereby to control the spice trade.
There are several reports in the history that the Portuguse needed help from Saint Thomas christians to beat the Arab merchants. In 1920s, the Portuguese sought help from Mar Jacob Abuna to persuade Saint Thomas Christians to trade their pepper to them. ( Antionio da silva Rego, Documenta cao para a Historia das Missoes do padruado Portugues do oriente, vol II Lisbon, 1948 p 357 cited by Pius malekkandathil Jornada of Alexis De Menesis:A Portuguese account of the Sixteenth Century Malabar, pXXIX )
Now, it is obvious that it was not to convert the Saint Thomas Christians to Catholicism, but to Latinise them, and to subjugate them under the Portuguese padruado. It was a cultural invasion to change their religious rite and rituals to control the community on the religious perspective and politically also for the colonial interests of the Portuguese.