It's claimed Hindu radicals assaulted the believers after saying they were trying to convert people to Christianity.
The incident happened on December 13 in Singareny Colony of Sarurnagar in India's southern city of Hyderabad.
Pastor Bhim Nayak, head pastor of Banjara Baptist Church, and fifteen of his church members were singing Christmas carols and visiting with other Christian families when they were attacked.
International Christian Concern says the group of extremist Hindus surrounded their vehicle and claimed the Christians were attempting to forcefully convert people to Christianity by singing Christmas carols.
The van's windows were smashed and the attackers dragged the Christians out into the street where they were badly beaten.
Pastor Nayak and four other were severely injured as the radicals used sticks and clubs during the attack.
The pastor is now in a critical condition in hospital.
International Christian Concern (ICC) said: "Pray for Pastor Nayak who remains in critical condition. Also pray for the ten other Christians injured in this attack.
"Remember India's Christians this Christmas, as this is likely not the only attack they will be forced to endure this holiday season."