A Romanian baby died after a baptism ceremony in which babies were immersed in holy water three times.
The 6-week-old baby was taken to a hospital with cardiac arrest on Monday and died a few hours later, the autopsy revealed fluid in his lungs, Agence France-Presse reported.
The tragedy pressured the Orthodox Church to change baptismal rules.
Prosecutors have opened a homicide investigation against the priest in the city of Suceava.
“The death of a newborn baby as a result of this practice is a huge tragedy,” said a post with an online petition for changes to the ritual. “This risk must be eliminated if the joy of baptism is to be triumphant.”
Thursday evening, the petition had collected more than 56,000 signatures, according to AFP.
One person online condemned the “brutality” of the ritual and another condemned the “stubbornness of those who think it is the will of God” to keep it up.
Local media have reported on several similar incidents in recent years.
Church spokesman Vasile Banescu said priests could pour a little water on a baby’s forehead instead of full immersion.
But Archbishop Teodosie, leader of the traditionalist wing of the church, stood his ground and insisted that the entire ritual should not change.
In Romania, where more than 80 percent of the population is Orthodox, the church is one of the most trusted institutions according to recent polls.