Military forces and police armed with assault rifles patrolled the streets leading to churches and stood guard outside the compounds. Everyone entering was required to produce identity cards and was body searched.
Volunteers were stationed at the gates of churches to identify parishioners and look for suspicious individuals.
Parking was banned near the churches and officials requested worshippers to bring along only minimum baggage.
Seven suicide bombers struck two Catholic and one Protestant church and three luxury hotels on Easter. The Islamic State group claimed responsibility for the attacks, carried out by a local radicalized Muslim group.
Sunday services were canceled in the two subsequent weekends for fear of more attacks, leaving the faithful to hear Mass via live TV transmission from the Colombo residence of Archbishop Malcolm Ranjith.
Church authorities are also mulling reopening church-run schools Tuesday if they can be satisfied with security.
President Maithripala Sirisena told The Associated Press last week that 99% of the remaining suspects in the Easter attacks had been arrested and their explosive materials seized, and it was safe for tourists to return to the Indian Ocean island nation.
Police say two previously little-known radical Islamist groups, National Towheed Jamaat and Jammiyathul Millathu Ibrahim, conspired in the attacks. Officials say Zahran Hashim, a vitriolic preacher from the country’s east, may have led the attackers and was one of the bombers to die.