Just like any historical event related to Malabar church each fraction keep its own version of this event.
The Coonan Cross Oath (Koonan Kurishu Satyam), taken on January 3, 1653, was a public avowal by members of the Saint Thomas Christian community of Kerala, India that they would not submit to Portuguese dominance in ecclesiastical and secular life. The swearing of the oath was a major event in the history of the Saint Thomas Christian community and marked a major turning point in its relations with the Portuguese colonial government. The oath resulted directly in the formation of an independent Malankara Church, with Mar Thoma I as its head, and ultimately in the first permanent split in the community.Historically the Saint Thomas Christians were part of the Church of the East, centred in Persia, but the collapse of the church hierarchy throughout Asia opened the door for Portuguese overtures. They came into direct communion with the Church of Rome through the Chaldean Patriarchate with the arrival of Mar Joseph Sulaqa and Mar Elias in AD 1554 and Mar Abraham(Died 1599).
With the establishment of Portuguese power in parts of India, clergy of that empire, in particular members of the Society of Jesus (Jesuits), attempted to Latinise the Indian Christians.The Portuguese started a Latin Rite diocese in Goa (1534) and another at Cochin (1558), and sought to bring the Thomas Christians fully under the jurisdiction of the Portuguese padroadoand into the Latin Rite of the Catholic Church. A series of synods, including the 1585 Synod of Goa, were held, which introduced latinized elements to the local liturgy. In 1599 Aleixo de Menezes, Archbishop of Goa, led the Synod of Diamper, which finally brought the Saint Thomas Christians fully under the authority of the Latin Archdiocese of Goa and replaced traditional East Syrian liturgy with Latinized liturgy. Widespread discontent with these measures led the community to rally behind the archdeacon, Thoma,However, many Saint Thomas Christians resisted the Portuguese padroado, including members of the old church hierarchy. In 1641 seething tensions came to a head with the ascendancy of two new protagonists on either side of the contention: Francis Garcia, the new Archbishop of Kodungalloor, and Archdeacon Thomas, the head of the old native hierarchy. In 1652 a man named Ahatallah, who claimed to be the rightful ""Patriarch of the Whole of India and of China", arrived in India. He was arrested by the Portuguese and was never heard from again in India, starting rumors that he had died or been murdered. This event combined with Francis Garcia's general dismissiveness towards the complaints of the Saint Thomas Christians, led directly to the swearing of the Coonan Cross Oath..On January 3, 1653 Archeadeacon Thomas and representatives from the community met at the Church of Our Lady in Mattancherry to swear what would be known as the Coonan Cross Oath.Those who were not able to touch the cross, tied ropes on the cross, held the rope in their hands and made the oath. Because of the weight it is said that the cross bent a little and so it is known as "Oath of the bent cross" (Koonen Kurisu Sathyam).
When news of these events reached Pope Alexander VII, he dispatched a Carmelite mission, headed by Jose de Sancta Maria Sebastiani. This mission, which arrived in 1661, organized a new East Syrian Rite church hierarchy in communion with Rome. By the next year 84 of the 116 Saint Thomas Christian communities joined this Eastern Catholic Church, known as the Syro-Malabar Catholic Church.In 1665, Mar Gregorios Abdul Jaleel, a Bishop sent by the Syriac Orthodox (West Syrian) Patriarch of Antioch, arrived in India, at the invitation of Thomas. This visit resulted in the Mar Thoma party claiming spiritual authority of the Antiochean Patriarchate and gradually introduced the West Syrian liturgy, customs and script to the Malabar Coast.The arrival of Mar Gregorios in 1665 marked the beginning of West Syrian association of the Thomas Christians. Those who accepted the West Syrian theological and liturgical tradition of Mar Gregorios became known as Jacobites. The remaining 32 communities eventually entered into communion with the Syriac Orthodox Church, introduced by Mar Gregorios Abdul Jaleel of Jerusalem.Those who continued with East Syrian liturgical tradition and stayed faithful to the Synod of Diamper are known as the Syro-Malabar Catholic Church in communion with the Roman Catholic Church. They received their own Syro-Malabar Hierarchy on 21 December 1923, with the Metropolitan Mar Augustine Kandathil as the Head of their Church.The Saint Thomas Christians by this process became divided into East Syrians and West Syrians.The split into Syro-Malabar and Malankara factions would be permanent; over the next centuries the Malankara Church would experience further splits and schisms.
Malanakara Jacobite Version.( part of oriental orthodox Syrian church of anthioch following west Syrian tradition )
In response to the continuous appeal of the Thomas Arkadiyakon (archdeacon), who was then giving leadership to Malankara Church; from the Patriarchate of Antioch came Mor Ignatius Ahattula in 1653. The tradition is that the Portuguese arrested him, tied him up and cast him in the Ocean. Consequently, the Syrian Christians get agitated and as a result, a large gathering of about 25,000 assembled at Mattancherry and took Oath at 'Koonan Cross' which happens to be known as the historical 'Koonam Kurisu Sathayam' in 1653 and declared that
Our future generations will ever be loyal to the throne of Antioch and we would not adhere to the Franks, nor accept the faith of the Pope of Rome.
Malanakara Orthodox Version.(independent oriental orthodox following west Syrian tradition )& Malanakara Marthoma Version. (A protestant reformed church following west Syrian tradition)
By the Father, Son and Holy Ghost that henceforth we would not adhere to the Franks, nor accept the faith of the Pope of Rome.
[Source: This reference from the The Missionary Register of 1822 ( Letter from Punnathara Mar Dionysious (Mar Thoma XI)to the Head of the Church Missionary Society.)]
Syro Malabar Version (Eastern catholic church following East Syrian tradition).
A protest took place in 1653 with the Coonan Cross Oath. Under the leadership of Archdeacon Thomas, the Thomas Christians publicly took an oath that they would not obey the Jesuit bishops [Sampaloor pahtiri]..The oath was not against pope or catholic church but against Portuguese authorities.
The situation is best explained by the Stephen Neill (an Anglican protestant missionary, from Scotland) in his book "A History of Christianity in India: The Beginnings to AD 1707".
"On january 1653 priests and people assembled in the church of Our Lady at Mattanceri, and standing in front of a cross and lighted candles swore upon the holy Gospel that they would no longer obey Garcia, and that they would have nothing further to do with the jesuits they would recognise the archdeacon as the governor of their church. This is the famous oath ofthe ‘ Koonen Cross ` (the open-air Cross which stands outside the church at Mattnchery.The Thomas Christians did not at any point suggest that they wished to separate themselves from the pope. They could no longer tolerate the arrogance of Garcia. And their detestation of the jesuits, to whose overbearing attitude and lack of sympathy they attributed all their troubles,breathes through all the documents ofthe time. But let the pope send them a true bishop not a jesuit, and they will be pleased to receive and obey him."
A History of Christianity in India: The Beginnings to AD 1707 By Stephen Neill page 326-327