Police have detained three suspects following the incident that took place outside Saint Rita Church on early Friday.
The 65-year-old victim, Gilbert Costa, has been admitted to Pabna Sadar Hospital with wounds on his head, hands and legs.
"Some men came to the church around 4am and asked for its keys. When Gilbert refused, they started hacking him with sharp weapons," said Martin Dominic Rozario, a member of the church management committee.
"The attackers fled when local shopkeepers, hearing Gilbert scream, came to his rescue," he added.
The shopkeepers informed his family of the attack, Gilbert’s wife Mary Costa told bdnews24.com.
Three suspects – ‘Rajib’, ‘Murad’ and ‘Farid’ - have been detained, said Pabna Additional Superintendent of Police Goutam Kumar Biswas.
"They are being questioned. All of them are from Laudia village," he said.
In June, last year, assailants hacked to death Nityaranjan Pandey of the Thakur Anukul Chandra Satsanga Paramtirtha Dham ashram in Hemayetpur Upazila of Pabna.
Machete- wielding attackers have carried out a series of attacks and murders over the past two years.
The victims included secular writers and bloggers, online activists, publishers, foreigners, members of religious minorities and rights activists.
Radical Sunni terror groups, Islamic State and AQIS (al-Qaeda in the Indian Subcontinent), claimed responsibilities for these killings, most of which took place in the country’s north-west region.
The government, however, has been denying the presence of global terrorist groups in Bangladesh.