Poland's Catholic Church has warned that modern Halloween rituals risk promoting the occult.
In a statement on its website, the Church said that celebrating Halloween could contradict Church teachings and Christianity.
One archbishop said the 31 October celebrations were promoting paganism to young people.
Archbishop Andrzej Dziega warned that Halloween was behind a "culture of death".
"This kind of fun, tempting children like candy, also poses the real possibility of great spiritual damage, even destroying spiritual life," the archbishop of Szczecin-Kamien wrote in a letter to be read out at Sunday sermons, according to the Polish Press Agency.
He wrote that "irresponsible and anti-Christian fun" introduced young people to a "world of darkness, including devils, vampires and demons" in the name of "fun".
The archbishop's statement echoes that of the Catholic Church in Poland, which warned that the "occult rituals" contradicted Church teachings and Christianity.
The All Saints religious feast is widely celebrated in the largely Catholic nation on 1 November, with relatives often travelling across the country to tend to the graves of late relatives, decorating them with lanterns and wreaths.
But the American-style practice of carving pumpkins and dressing up as monsters, ghouls and devils the night before has also become increasingly popular.