http://www.globalsecurity.org/military/world/para/nlft.htm
The National Liberation Front of Tripura (NLFT) was formed in December 1989 for the purpose of seceding from India in order to create an independent Christian fundamentalist state of Tripura. The group was banned under the Unlawful Activies Prevention Act of 1967.
The headquarters of NLFT is located in the Khagrachari district of Bangladesh, about 40-45 km southeast of Simanapur.
In Tripura a systematic surrender of arms by a faction of NLFT insurgents and NLFT fringe groups is due to the increased security pressure and to infighting within NLFT insurgent ranks. Since 2000 a few hundred militants have surrendered in small groups to the security forces, handing in their weapons. The NLFT leadership engaged in peace talks with Mizoram Chief Zoramthanga in April 2001, however the NLFT has not promised acceptance of any future peace process.
The NLFT has set up a number of camps in Bangladesh's Chittagong Hill Tracts (CHT), in the Sylhet, Maulavi Bazar, Habiganj and Comilla regions. NLFT also has ties with Pakistan’s external intelligence agency, the Inter Services Intelligence Agency (ISI).
So what exactly is your point?
I would suggest that the problems in India's North-East is more due to ethnic diffences between them and the rest of India (note that they even look different from most Indians) and due to the fact that they are isolated from the main part of India -- almost separated by Bangaldesh. Hence they were linguistically, racially, ethnically and economically different from the main group of Indians. Since the previous governments didn't bother to integrate them, they felt different and looked for Independent nations. However, if you notice, since India has liberalised and concentrated more on making the North-East feel at home with the rest of India, these movements have died out. The Baptists DID exacerbate it, I agree, but they weren't the cause.