There's so many different groups I don't know what is what.
Indian Christians can be broadly classified into two:
A) Indian Christians under the St. Thomas tradition
B) Indian Christians evangelized in modern times by Western Missionaries
All 'St. Thomas Christians'
don’t share the same faith. They fall into five broad categories:
1) Oriental Orthodox Communion
a) Malankara Orthodox Syrian Church (autocephalous and under the Catholicate of the East, since 1912)
b) Malankara Syriac Orthodox Church (also known as the Jacobite Church; autonomous under the Catholicose / Maphrian, but under the spiritual authority of Patriarch of Antioch of the Syriac Orthodox Church)
2) Chaldean Church
aka Church of the East (also known as the Nestorian Church)
3) Roman Catholic Communion
a) Syro Malabar Church (this is an Eastern rite Catholic church, that officially joined RC in 1599 as per the Synod of Diamper. They continued to be administered by European Catholic Bishops for a long time. This Eastern rite and local hieararchy was only established in 1923. In 1992 this Eastern rite was raised as a Major Archiepiscopal see)
b) Syro Malankara Church (this is an Eastern rite was established in 1932, when Mar Ivanious a Bishop of the Malanakara Orthodox Church left the church and joined Rome. In 2005 this Eastern rite was raised as a Major Archiepiscopal see. The Major Archbishop of this rite started using the title Catholicose)
Of these two Eastern rites, 3a uses the vestments and traditions of the Chaldean chuch and 3b uses the vestments and traditions of the Malankara Syriac Orthodox church.
4) Anglican Communion
a) Marthoma Syrian Church: (under the influence of British missionaries, a Bishop of the Malankara Syriac Orthodox Church started teaching the Protestant reformed theology in the 1860s. This bishop was excommunicated from the Orthodox Church. The Marthoma Syrian Church uses the vestments and 'reformed' liturgy omitting intercessions of saints, prayers for the departed etc of the Orthodox Church.
5) Independent Oriental Orthodox
a) Malabar Independent Syrian Church of Thozhiyur : (In 1771 a schism occurred between two Bishops of the Malankara Syriac Orthodox Church. This schism led to the creation of this church. However this church remained in communion with the Malankara Orthodox Church till 1870s. During that time this church started more closely aligning with the reformed 'Marthoma Church'. However this church has not yet formally accepted the reformed teachings.
Now the 'Indian Christians evangelized in modern times by Western Missionaries'
B. The two most important churches in this category are:
1) Latin Catholics
- evangelized by the Portuguese Catholic missionaries.. starting from the 1500s
- evangelized by the British starting from the 1800s
a) CSI - Church of South India
b) CNI - Church of North India
These two churches form the 'Anglican Church of India'.
3) All sort of Pentecostal groups, Jehovah Witness, Mormons etc (American missionaries starting in the 1900s)