Members of the Baptist Church pinned a piece of black cloth on their shirts and held mass prayers in all the local churches in the morning services.
In a message distributed to the local churches, BCM General Secretary Rev H Lianngaia said that Indian Constitution in 1950 allowed only Hindus to become Scheduled Caste while the amendment in 1956 allowed Sikhs and Buddhists.
"Christians and Muslims were not allowed to be given Scheduled Caste status," he said.
The Constitutional provision hindered missionaries in their missions to convert Scheduled Caste people like the Dalits as they ceased to enjoy the status once they converted to Christianity, he added.
The BCM described the provision as biased and against the spirit of secularism.