This public declaration marked their refusal to submit to the authority of the Jesuits and the Latin Catholic hierarchy, as well as their rejection of Portuguese dominance in both ecclesiastical and secular matters.

The Saint Thomas Christians, whom the Portuguese referred to as "Nestorians," largely resisted these latinizations, as they were seen as an infringement on their longstanding religious customs.

[4][5][6][7][8] A key figure in this resistance was Ahatallah, a Syrian bishop who arrived in India and was regarded by many Saint Thomas Christians as a potential leader capable of restoring their traditional practices.

His capture by Portuguese authorities, who feared his influence, and his subsequent mysterious disappearance only fueled further resistance among the Saint Thomas Christians.

The disappearance of Ahatallah played a direct role in prompting the Coonan Cross Oath, as the community feared the complete erosion of their traditions under Portuguese rule.

[15] However, with the establishment of Portuguese power in parts of India, the clergy of that empire, in particular members of the Society of Jesus (Jesuits), attempted to Latinise the Indian Christians.

The padroado rule of the Portuguese was only momentary, for the feelings of resentment and the desire to regain independence among the Thomas Christians were very real and could not be contained for long.

[18] While at Mylapore, Ahatalla met two Syrian Christian deacons, viz: Chengannur ltty and Kuravilangad Kizhakkedath Kurien from Malankara, who were on a pilgrimage to the tomb of St. Thomas and sent a letter through them to the Church of Malankara saying:Behold, I Ignatius, Patriarch of All India and China, send to you a letter through the clerics who came here from your place.

Several letters were sent to all the civil and religious authorities in Cochin, for at least an opportunity to visit Ahatallah, to examine his credentials and to verify his identity, promising that if he was found an imposter, they would be the first to press for his punishment.

[19] Jacob Kollamparambil, a Church historian says that when the ship carrying Ahatallah reached Goa, he was handed over to the inquisition, and he was kept in close custody in the Jesuit house there.

Joseph Thekkedath, another Church historian narrates that Vincent De Paul, who met Ahatallah at Paris, mentions him in the following words "There remains in this city a good old man of eighty years, a foreigner, who was lodging with the late monsignor Archbishop of Myra.

[21] The treatment of Ahatalla, shocked the Thomas Christian community, and their wounded feelings effervesced into a mass upsurge that heralded the breaking off from the Padroado of the Portuguese Crown and the Jesuits.

[22] "In case the patriarch cannot be produced, he having been killed by the Paulists [Jesuits], let any other person of the four religious orders come here by order of the supreme pontiff, a man who knows Syriac, and can teach us in our offices, except the Paulists, whom we do not at all desire, because they are enemies of us and of the church of Rome; with that exception let anybody come, and we are ready to obey without hesitation.

On 3 January 1653, Archdeacon Thomas and representatives from the community assembled at Our Lady of Life Church, (Nossa Senhora da Vida) at Mattancherry to swear "never to submit to the Portuguese".

Standing in front of a granite cross, the oath was read aloud with lighted candles, with the Archdeacon and the leading priests touching the Bible.

The event broke the 54-year-old Padroado supremacy of the Portuguese Crown over the Thomas Christians which was imposed at the Synod of Diamper in 1599.

This letter advised that in the absence of a bishop, twelve priests could lay hands on Archdeacon Thomas, which would suffice for episcopal consecration.

[29] He further highlights that the second letter, which served as basis for the enthronement of the Archdeacon Thomas, does not mention him by name, but on the contrary instructs the Saint Thomas Christians to appoint Deacon George Parambil as the Archdeacon and to establish a body consisting of 12 presbyters in order to elect the Metropolitan after the death of Francis Garcia.

Before leaving Kerala, on 1 February 1663 Sebastiani consecrated Palliveettil Chandy as the Metran of the Thomas Christians who adhered to the Church of Rome.

In 1665, Gregorios Abdal Jaleel, a bishop sent by the Syrian Orthodox Patriarch of Antioch, arrived in India and the faction under the leadership of Thoma I welcomed him.

[42] This visit of Abdul Jaleel gradually introduced the West Syriac liturgy, customs and script to the Malabar Coast.

[50] But following the death of Palliveettil Chandy, in 1687, the church was again fallen under the leadership of foreign missionaries for a long time[51] and had to face challenges to their eastern, Syrian and indigenous heritage and rite.