A new era dawned in the religious horizon in India, by virtue of the discovery of the new sea-route to India by the Portuguese Admiral Vasco de Gama who landed in Calicut in 1498 and made friends with the Zamorin, the ruler of Calicut. Gama was followed by Cabral who had with him priests both secular and Franciscan. In Calicut they set up an Oratory in 1500 and began evangelization with the help of a Brahmin convert by name Michael a S. Maria. A fortress was built in Cochin in 1505, and Cochin became the seat of the Portuguese Viceroy from 1505 to 1530 when it was shifted to Goa.

When the Portuguese came to India, the Malabar Christians spontaneously welcomed and treated them as brothers in faith. The Portuguese soon realized that the Thomas Christians were a powerful community and their support would be essential to their commercial, political and religious interests.

The King of Portugal sent more priests to Kerala for missionary activities and they tried to rejuvenate the faith and religious practices of the ancient Christians of St. Thomas. Leading a Jesuit group to India, St. Francis Xavier, popularly known as the Second Apostle of India, landed in Goa in 1542, and arrived at Cochin in 1544. His mission in Travancore was a splendid success, converting several thousands of people to Christianity in the sea-coast.

Although the Portuguese missionaries were happy to meet Christians in the midst of Hindus and Muslims, they very soon noticed the differences in ritual and liturgy which were intolerable to them. They wanted unity in the Kingdom of God and decided to take measures to achieve this goal.

From the beginning of the 16th century the Portuguese began to exercise their power in India. They baptized several thousands of non-Christians in the Latin rite. Cochin in Malabar, and Goa, outside Malabar, were their politico-ecclesiastical centers. Goa became a bishopric in 1534, and a metropolis in 1558 with Cochin as its suffragan see erected in the same year. Both these sees were under the Padroado (Patronage) of the Portuguese crown. With certain obligations the Portuguese crown had the privilege to nominate Prelates for these sees. Goa's jurisdiction extended from the cape of Good Hope as far as China. Cochin's jurisdiction was roughly from Canannore down to the south and up to the south east.

With the rise of Goa as the chief seat of Portuguese political and ecclesiastical power in the East, they wanted to bring the Syrian Church directly under Rome and thus under Goa. The Portuguese adopted several coercive measures, including the kidnapping of Syrian bishops, accusing the Syrian Church of heresy and imposing sea blockades to prevent the importing of prelates from the Eastern Patriarchs. Although the Portuguese clergy contributed much to the spiritual uplift of the faithful here, the ancient Christians could not appreciate the Latinising policy of the Portuguese. The policy was so intolerable to the native Christians that it led to an open rupture.

For the Portuguese in general the ideal of a "true" Catholic was to be of the Latin rite. The Padroado was their idol. They, therefore tried every means, even illegal and unjust, to Latinise the Thomas Christians and to reduce them under their Padroado jurisdiction. They trained some Thomas Christian youths in their seminary at Cranganore according to the Latin rite, and sent them to Portugal. In the beginning there was some mutual understanding. But gradually, step by step, the Portuguese, became aggressive. They had by then with them some Thomas Christian priests who were trained in their seminary at Cranganore, and who were ordained in the Latin rite. They contended that the Prelate of Goa was the Prelate of All-India in opposition to the All-India of the Metropolitan of the Thomas Christians. They could not suffer the existence in India of the jurisdiction of the Chaldean Patriarch. The Thomas Christians however, would not part with the "Law of Thomas". i e., the Chaldean liturgy and rite with the Christianized Indo-Malabar customs, nor would they give up their Chaldean Patriarch and the Chaldean Prelates. The Portuguese smelt Nestorian heresy and schism in everything even in the liturgical and social peculiarities of the Thomas Christians, while the Chaldean Prelates became their special target. The division of the Chaldean Church under the Patriarchs of the line of Sulaqa, and under those of the line of Sulaqa's rival worsened the situation in favor of the Portuguese. The Thomas Christians were legally under the Prelates who were sent by the Patriarchs of the line of Sulaqa who had Roman confirmation.

There appeared in Malabar some Prelates who were from under the Patriarchs of the other line. This and books that contained passages dealing with St. Cyril, Nestorius etc., as well as with Christological doctrine which they did not understand properly, gave the Portuguese ample matter for self justification. The Chaldean Prelates in spite of explicit or equivalent Papal recommendations, were imprisoned, or expelled from Malabar as Nestorian heretics. After Mar Jacob's death (1950-52), the Thomas Christians had no bishop for a few years. Having despaired of getting bishops from the Seleucian Patriarch they showed themselves inclined towards the Portuguese. The Portuguese exerted all their influence in Rome, and by the end of the 16th century, and by the beginning of the 17th century they gained much of what they were trying for.

Synod of Diamper

The Portuguese missionaries wanted to do away with Chaldean jurisdiction over Malabar and wield their politico-religious power over the Thomas Christians. The archbishop of the Thomas Christians, Mar Abraham, sent by the Catholic Chaldean patriarch, was found guilty of heresy by the Portuguese missionaries. In the light of the report of the missionaries, in 1595, Pope Clement VIII sent two apostolic briefs to Archbishop Dom Menezes of Goa. These were only to inquire into the life and doctrine of Abraham and, if he was found guilty or if he died, to appoint a Vicar Apostolic. Mar Abraham died in 1597, and then Dom Menezes, the Portuguese archbishop of Goa, and the ex-officio political ruler during the absence of the Portuguese Viceroy of Goa, entered Malabar, claimed he had authority from the Pope, and visited the churches of the Thomas Christians exercising jurisdiction. Using force, he opened churches and exercised jurisdiction over them by giving confirmation. He did not mind the excommunication served to him by the archdeacon. Visiting churches, he held three ordination services and ordained at least a hundred, making them condemn Nestorianism. He thus gained to his side those who were ordained and their relatives. The Malabar kings, especially the one of Cochin, also were threatened and won over.

Dom Menezes made hasty preparations for his synod to which, sub poena excommunicationis latae sententiae, were summoned all priests and other clerics and four lay men elected from each church, even from the churches he had not visited. Around 153 priests and 671 laymen (elected ones and specially invited ones) from some 64 churches in 168 villages met at Diamper (Udayamperoor) in the territory of the king of Cochin. The synod was held in June (20-29), 1599, at which the Thomas Christians had to sign the Profession of Faith at the beginning, and the decrees at the close of the synod. They were also to condemn the Patriarch as a heretic and schismatic and to swear they would not accept any bishop except the one immediately nominated by Rome. The Patriarch thus condemned was Denha Simon who was in explicit communion with Rome being also honored with the sacred Pallium from the Pope.

Menezes passed decrees using force which practically converted the Malabar Church into a branch of Latin Church. The synod enacted fundamental changes in the rite, liturgy and ecclesiastical laws of the Thomas Christians. Portuguese and Latin laws and customs supplanted all others. This Latinization was mainly based on the discipline of the Council of Trent.

The Synod cut the link of the Malabar Church with the Mesopotamian Church which was at that time in full communion with the Church of Rome. This Synod was publicized in the west as the conquest of heretics for the Catholic faith. It should be noted that there is a contradiction between this notion and the fact that the Thomas Christians were summoned to the Synod under the pain of "excommunication"! Click here to see the Catholicism of the Thomas Christians.

On the other hand, the laws of the Synod of Diamper had no binding force as it was not a lawful synod because of lack of authority on the part of those who convoked it, absence of intention on the part of those who attended it, lack of form in the manner of conducting it and lack of integrity in the text promulgated. It is Possible that the laws concluded by the prelates who ruled the Malabar Church and which were all Latin in form and content were made under the erroneous assumption that Latin laws were universal.

Roz S.J. and Campori S.J. who were present at the synod, clearly state in their letters to the General of the Jesuits and his Assistant in Portugal that the "synod" was not "in forma". According to these letters 1) the Thomas Christians were not consulted in the "synod", 2) they understood nothing of all that was decided upon there, 3) there was no synod, but only reading of regulations which were not understood by those concerned, 4) Dom Menezes said he behaved like that just to show the way of salvation to the assembled without hindrance, 5) there were many things in the decrees unacceptable to the Thomas Christians, 6) those who assembled put their signature to the acts only at the insistence of Roz S.J., 7) the zeal of Dom Menezes was preposterous, 8) Dom Menezes made additions to the acts after the "synod" was over, 9) Dom Menezes obtained from Roz S.J. the signatures of the assembled detached from the original and had them attached, to his copy prepared to be sent to Rome for approbation, 10) the authors of the letters pray that the Pope may not approve the synod to rectify which they say, Roz S.J. (as bishop) had celebrated a synod at Angamaly "in forma" with the satisfaction of all, undoing certain things which Dom Menezes had ordered at Diamper. Such is the "synod" of Diamper, the acceptance of which was later on insisted upon even as a condition for the reunion of non-Catholic Thomas Christians. There is no document which says that the Holy See ever approved the "synod" of Diamper.

The Synod of Diamper, although not legitimately and properly conducted, is the first formal and canonical endeavor in Malabar Church on such a large scale. It has great historical value. It brings to light many ancient practices of the Thomas Christians. This has become the unique and sole important document in this respect because many of their other books were burned after the synod. The synod helped the organization of the diocese into parishes and their administration. It helped the evangelization of the low castes and also the raising of their social status. Many of the canons and decrees of the synod were just reproductions of the Councils of Trent, Lateran and Florence. Unfortunately the Synod of Diamper effected Latinisation in the Malabar Church, and later the Latin jurisdiction was imposed over this Church.

Roz S.J. was nominated as the first Latin Bishop of Angamaly as successor to Mar Abraham, on Nov. 5, 1599. The Metropolitan see of Angamaly was reduced to a suffragan see of Goa under the Padroado on Dec. 20, 1599, and the title of Angamaly was changed into that of Cranganore. On Aug. 4, 1600, the Padroado of the king of Portugal was also extended over Angamaly. The Thomas Christians were thus placed under Latin jurisdiction. Thus the Portuguese gained all that they ware trying for.

If Roz, S. J., had respected and kept intact the liturgy of the Thomas Christians, and had left the Archdeacon to govern according to the "Law of Thomas", things would have proceeded peacefully. But, retaining the Syriac language, he Latinised and mutilated the liturgy adding to it translations from the Latin liturgy. He curtailed the time-honored powers of the Archdeacon treating him as a Vicar General of the Latin Church. Quarrels and unrest, excommunication and absolution of the Archdeacon etc., were the consequences.

The Latin-oriented policy of the prelates and the subsequent restless state of the community, which saw several of its customs and privileges disregarded, caused discord and tension. This held back the laity from several positive contributions which they could offer. As a result of the forced Latinization, an open revolt of Thomas Christians broke out against the Jesuit Latin bishops, which led to the vertical split of the community itself in 1653. The dissension after the oath (in 1653) of non-allegiance to the Latin prelates, caused a wound still unhealed in the community. Efforts were concentrated, first, to reconcile the split, and when that failed either group tried to gather more adherents to its side. For more details, see The Orthodox Churches in India.