Amidst an uproar in the the House by opposition members, the bill was passed by voice vote without holding discussions, prompting the Congress to later submit a memorandum to Governor Balram Jakhar asking him to return it.
The bill provides for a person wishing to change his religion to voluntarily inform the district magistrate of his intentions, sources said adding the priest or organisations performing the conversion rituals were also required to inform the authorities about it a month in advance.
Police were given the task of verifying the credentials of the priest or the organisations ahead of the conversion and that this was not being done by force or with allurement.
The bill includes provisions for penal action like one year's imprisonment and a fine against priests or organisations that perform conversions without following due procedures and a fine of up to Rs 1000 for persons who fail to inform authorities about their intentions to adopt another religion, sources said.
While the government claimed existing laws are inadequate to check conversions by force or allurement, the Congress termed the move an "interference with religious freedom and human rights".
The BJP is "practising vote bank politics and wants to spread communal hatred", Leader of Opposition Jamuna Devi said in the memorandum, adding "it aims to exploit the Christian community and tribals through the bill".