According to the census, the community of Christian In Kerala is the third-most practiced religion with 19% of the population. The history of christians in Kerala goes back to the earliest period of the Church itself. In the absence of clear historical records, it is believed that Apostle of Jesus, St.Thomas himself, introduced Christianity in India in the year 52 A.D. The early Christians (St.Thomas Christians) were called Syrian Christians because they followed the Syriac liturgy, a dialect of Aramaic, the language of Jesus.
With the arrival of Portuguese (1498) and the establishment of their political influence the Latin rite emerged as an important factor and a large community of Latin Christians sprang up and grew, particularly in the coastal areas.
The work of St.Francis Xavier and the synod of Diamper (1599) played an important part in the Latinisation of the church. In the beginning of 19th century, when the British spread its influence in Kerala, the Church Mission Society (CMS) of London actively associated them in the workings of Syrian Church. After some years of close co-operation, the missionaries broke their connection with Syrian Bishops and church. It was on their initiative the Anglican Church came into existence. Some priests of the Syrian Church under the influence of missionaries advocated reforms, including the replacement of Syriac by Malayalam, which was disfavored by Bishops and Clergy of Syrian Church. Christianity in Kerala is not a homogenous entity.
Kerala Christians are divided into Syrian, Latin and New Christian groups which may be regarded as castes. Spear headed by the Kerala Christians, who start schools, help the poor and 'salvage' the people in myriad ways. The Christians in Kerala can be broadly categorized into three: Syrian Christians who are believed to have been converted from the upper castes by Apostle St. Thomas, Latin Christians in Kerala who were converted mostly from lower classes by St. Francis Xavier in the 16c and Dalit Christians who were converted in the 19c by the Anglicans and in the 20c by the Catholic denomination of the Syrians. The labels Syrian and Latin came about because of the respective languages that were used in liturgy.
The two groups of the Syrian Church, namely the Jacobite Syrians and the Orthodox Syrians continued court battles and finally in 1960 the Supreme Court of India ruled putting an end to the litigation. Again there are two divisions, the Orthodox Syrian Christians owing allegiance to the Catholicos of the East and the Jacobites Syrian Christians owing allegiance to the Patriarch of Antioch in Syria. Very recently the supreme court of India has once again ruled putting an end to legal struggles between those two groups and recognizing the legitimacy of the Catholicos.
The Roman Catholic Church accepted allegiance to Pope and came to be known as Syrian Roman Catholic. There are Roman Catholics converted by European missionaries known as Latin Roman Catholics. There is also Roman Catholic group mentioned earlier called "Reethu" or the Malankara Syrian Rite. The Roman Catholic Church went through it's own evolutionary struggles after the Portuguese power declined in India.
Syrian Christians celebrate all Christian religious days. The more orthodox people maintain Lent for twenty four days prior to Christmas and fifty days prior to Easter.