On 20 June 1599, the Synod of Diamper began in Udayamperoor/Diamper in Kerala, India] under the leadership of Archbishop Aleixi de Menezes.*
When the Portuguese encountered the Thomas Christians after the arrival of explorer Vasco de Gama in 1498, the Thomas Christians were part of the Assyrian Church of the East or Chaldean Church.* As a result of Portuguese missionary activity many Thomas Christians were influenced by the rituals and practices of the Roman Catholic Church and in 1552 a group of Thomas Christians entered into communion with the Pope.
However, the Portuguese hierarchy in India wanted to bring the Thomas Christians into closer jurisdiction of the Latin hierarchy and replace the Assyrian/Chaldean liturgy with that of the Roman Catholic Church. Many of the local customs were condemned as heretical and many of the liturgical books of the Thomas Christians were ordered corrected or were burnt.
The Archbishop summoned all priests to the Synod of Diamper under pain of excommunication. 130 priests and 660 laymen met at the Synod which lasted until 26 June 1599. The Synod, presided by the Archbishop of Goa, condemned the Chaldean Patriarch who was in communion with Rome to be a heretic and a schismatic, Thomas Christians were not to accept any bishop except one immediately chosen by Rome, and the Latinization/adoption of Roman Catholic traditions and practices was confirmed.
More recently, the studies of Bishop Jonas Thaliath has demonstrated that the Synod of Diamper was invalid on the grounds that the Synod was convoked without the proper authority from Rome and did not follow Canon Law.
The effect of the Synod was to provide a greater push toward the further Latinization of the Thomas Christians and to separate them from their historic ties to the Chaldean Church. As the Catholic Encyclopedia notes, “The only case in which an ancient Eastern rite has been willfully romanized is that of the Uniat Malabar Christians, where it was not Roman authority but the misguided zeal of Alexius de Menezes, Archbishop of Goa, and his Portuguese advisers at the Synod of Diamper (1599) which spoiled the old Malabar Rite.”
Moreover, hostility from the Thomas Christians to the Portuguese treatment led to the Koonan Kurishu Satyam (Koonan Cross Oath) in 1653. At which some of the Thomas Christians swore that they would not obey the Portuguese bishops or the Jesuit missionaries. This will lead to a split among the Thomas Christians between the Syro Malabar Catholic Church which followed the Synod of Diamper and the Syriac Orthodox which did not.
The history of the Syro-Malabar Church
*The native Christians of India called themselves Thomas Christians because there tradition states that they were evangelized by Thomas the Apostle.
catholicunderthehood.com 
4 Comments
The Synod of Diamper wanted to introduce real Christianiy by removing heresy and other pagan customs. Archbishop Menzes wanted to correct what he termed the lapses and errors of the Indian Christians. Syrian Church in Kerala was functioning rudderless for centuries without any guidance about Christian doctrines, liturgy and church discipline either from Chaldea or Rome.. The two last Syrian bishops were Mar Joseph Sulaka and Mar Abraham; both arrived in Malabar after the arrival of the Portuguese. But their bona fides were under a scanner. Mar Joseph was of a dubious character and he changed sides quite often… After a brief interlude, an imposter named Abraham from Mesopotemia entered Kerala undetected, sent by Simeon the Nestorian Patriarch.This Abraham, through triickery, deception and double- dealing, succeeded in obtaining his nomination and creation as Archbishop Angamale from the pope, with letters to the Archbishop of Goa, and to the Bishop of Cochin dated 27 Feb., 1565.. But soon he returned to Nestorian teaching and practices. To avert a crisis in the Church, Father Valignano, then Superior of the Jesuit Missions, persuaded Mar Abraham in 1583 to assemble a synod. Mar Abraham openly abjured Nestorianism, and professed the Catholic faith, It is against this confused backdrop that we have to analyse the historical decisions of the Synod of Dampier.
The Synod condemned multitude of Hindu beliefs, especially those related to ‘transmigration,’ ‘fate’ and ‘astrology’ . Since most of the converts were from Hindu untouchable castes, Hindu rituals, superstition and beliefs continued to exist among Christians. The original immigrants who had married untouchable wives and their children were given higher caste status by the rulers. When Francis Xavier visited Kochi there were Mukkuva Christians belonging to Syrian church. But the offspring of untouchable converts in Syrian church followed the heathen practice of purification on touching other Hindu sub castes following Hindu customs. Since ‘touching’ , is mentioned in the Synod decision, it is obvious those sub castes were working in the churches or houses of Christians. On the other hand, in Hindu Brahmin and Nair areas the untouchables and subcastes were barred from entry to avoid touch and sight pollution. The Synod condemned such barbarous customs . Lower caste Hindus, especially Ezhavas, Pulayas and Parayas tied thali’ around neck of bride on the occasion of marriage’ The Synod prohibited such practice among Christians. Hardworking labour castes such as Ezhavas, Parayas and carpenters had to take bath after their work before entering their caste temples. The Synod declared it unnecessary. Christians are to remain clean always and can take bath everydat without giving specific time. The Synod condemned all practices of converted untouchables relating to death, puberty and consulting astrolagers but to depend on God’s will. The Synod also condemned distortion of Christian beliefs such as the annunciation of the angel was made in the Temple of Jerusalem which contradicts the Gospel of St. Luke, which says, it was made in Nazareth. The Synod also condemned the following heretical ideas of St. Thomas Christians.
Joseph had another wife and children when he was betrothed to Mary.
Child Jesus was reproved for his naughty tricks.
Child Jesus went to school and learned from them.
St. Joseph, suspecting Mary of adultery took her to priests, who gave her the water of jealousy to drink; that Mary brought forth with pain, and parting from her company, not being able to go farther, she retired to a stable at Bethlehem.
None of the saints is in heaven, but are all in a terrestrial paradise, where they should remain till the Day of Judgment.
Archbishop Menezes was the chief architect of the Synod. He was a sincere Christian who wanted to bring the lost sheep (St. Thomas Christians) to the common Christian fold. He was consecrated Archbishop of Goa in 1595, when he was only 35.In 1612 Aleixo de Menezes was appointed Archbishop of Braga, Portugal. He was viceroy of Portugal during the Iberian Union from 1612 to 1615. He died in 1617, his remains are located at the Populo Church in Braga.
I would be genuinely curious if you could reference source texts for your position. My sources indicate that the Synod was not even considered valid in the West.
If we look back, history will tell us that St. Thomas visited Kerala from Mylapore after making several conversions in Persia. This can be proved from the presence of Christians in Gondophornes’ empire. The claim that St. Thomas visited Palayur and ordained four families as clergies from the Brahmin families of Pakalomattom (Pakalomattam) , Kalli ,Sankarapuri ,Kalikavu is a laughable figment of imagination because there were no Nambudiris in Kerala in 1st century A.D. The earliest notice of the existence of Christianity in Ceylon is that of Cosmos Indoplustes, an Egyptian merchant, and afterwards a monk, who published his ‘Christian Topography’. He says that Persian priests and merchants in Ceylon were mere sojourners and they did not marry the local people. That was the case in Kerala too. After a long interval after St. Thomas’ martyrdom, Persian missionaries came to Kerala occasionally and there was no mass migration of Persians or Assyrians to Kerala. So it becomes crystal clear that Christians converted by the Persians in Kerala were local residents. In those days of religious orthodoxy and caste consciousness, upper castes such as Nambudiris or Nairs could not be converted. But lower caste people who were in constant contact with the Persian missionaries such as fishermen (mukkuvas), barbers, dhobis, day labourers (parayas), coconut climbers in their compound (Ezhavas) and such others were made Christians.
The Portuguese occupation of Kerala for 150 years elevated all outcaste converts to a superior status. Even the Kochi Raja was made a subordinate vassal. Lower caste converts were appointed in the army and police by the Portuguese and this made even Nambudiris and Nairs to be afraid of them and respect Christian army and police officers. Christians were appointed in Portuguese factories as accountants, messengers, planters in estates, cooks (famous Portuguese cuisine in Christian homes today, instead of kappa and fish, the staple food of Syrians), widespread intermarriage, officially instituted by Albuqurque, with low caste Hindu converts producing a new community with white colour and good physical features), brokers (tharakans), traders etc., It was this elevated status given by the Portuguese that made Syrian Christians claim Nambudiri, Jew and now Assyrian descent, although all were from lower castes. It was during this period and early British rule that family books like Nirananm Granthavali and folk songs like Margam Kali emerged extolling higher caste and social status of Christians. But these claims were false, manipulated and fanciful versions because they were not contemporary accounts when St. Thomas and other Persian missionaries were in Kerala, but produced several centuries after their departure. Rev. C.Y. Thomas in his book on Madhya Kerala Diocese points out: “Despite persistent persecutions, slave schools were opened in several places and the movement spread, gathering momentum with each new step. It is recorded that nine years after the first baptisms the Bishop of Madras visited the Mass Movement area and confirmed over a thousand outcaste Christians.”
Who are the present descendants of Ezhava, washerman, outcastes and slaves converted by Persian and CMS missionaries? Hundreds of year’s existence has wiped out their untouchable past and now they flaunt the common community name of Syrian Christians, with the fake claim their ancestors were Nambudiris and Jews. When St. Xavier visited Kerala, he was greeted by two Christians. At that time the only church in Kerala was Syrian church and the two Christians were mukkuvas. So even before the arrival of CMS missionaries, Syrian church converted lower castes. The vast crowd of 20,000 Christians at the time of Coonen Cross pledge is a clear evidence that they were all lower castes, mostly fishermen of the beach, because 20,000 Nairs or Nambudiris or Jews could not be collected instantly by Archdeacon Thomas for the pledge.
Converts from lower castes always want to get recognition as Syrian Christians.Unfortunately the conversion from lower castes started only after arrival of the Portugese and others.Till then the Syrian Christians were an endogamous community. Portugese always wanted to pull down the local Christians for establishing their hegemony. DNA tests have also established the commonality between Syrian Christians and other upper castes….Syrian christians claim to have converted from Nambudiris and do not claim that they are descendants of persian or assyrian migrants (Their parents are fully Indian).