They were imprisoned in connection with arson, rioting and the torching of houses in Jarkinaju village, in Orissa state, on 25 August 2008.
Ten others accused in the case were acquitted due to lack of evidence, Christian Solidarity Worldwide reports.
At least 90 people were killed when violence broke out across Kandhamal district in 2008 following the assassination of a local Vishwa Hindu Parishad leader by Maoist insurgents.
It was the worst outbreak of anti-Christian violence since India gained its independence, with an estimated 54,000 people forced to flee from their homes.
Despite the level of violence, few suspects have been convicted. Most have either been dismissed or acquitted, leading to outcry from human rights activists.
Dr John Dayal, a Member of the Government's National Integration Council (NIC) who has visited Kandhamal regularly, said, "Justice must be done, and must be seen to be done.
"The aggregate of justice in the fast-track courts in Kandhamal does not inspire a sense of confidence and closure among the victims.
"Many killers are roaming free, and a Member of the Legislative Assembly is at large after his conviction, because the courts seem to think he is too important to be incarcerated."
David Griffiths, CSW South Asia Team Leader, said, "Any convictions in Kandhamal mark a step forward, and credit must also be given to the human rights defenders providing essential legal aid to victims and witnesses.
"However, we continue to urge the state administration in Orissa to fight against the prevailing impunity, because the victims deserve justice, and because the rule of law is the essential foundation for peace."