The interior of St. Sebastian church was destroyed by the fire on December 1 after police took 10 hours to respond to calls.
Initially officers said the blaze was caused by faulty wiring but agreed to open an investigation after cans of kerosene were found.
Cardinal Oswald Gracias, Archbishop of Mumbai, told Asia News the attack must be 'strongly condemned'.
"I'm completely shocked and deeply saddened at this arson attack," he said.
"While I do not want to attribute communal motives, but this act of deliberate torching of a Sacred Place of worship, is completely unacceptable and cannot be condoned.
"People are revolted and feel vulnerable, whenever the miniscule Christian community is targeted".
When the fire was out Christians took the streets to protest and call for better protection for Christians.
Cardinal Garcias added: "I request the authorities to significantly speed up apprehending those responsible and charge them under stringent sections of the law.
"All Places of worship in India must be respected in our multi-religious society and the authorities must remain on the watch to prevent the recurrence of such traumatic incidents, which are sources of division and destabilization of the society and detrimental to national integrity and the harmony of the nation.
"This attack on the Place of worship goes against the very progress and development of the nation."