Cardinal Sean P. O’Malley is warning parishioners that legalizing recreational pot could lead the state deeper into the raging opioid crisis — a rare political appeal from the religious leader that comes as polls show the measure could pass.

“If this referendum is approved, there will be an extremely damaging impact on our society, particularly children and young people,” O’Malley’s statement said. “As our society battles the devastating opioid crisis, which each day claims the lives of those who have been snared in the trap of addiction, it is beyond reason that we would legalize a gateway drug that, in addition to its own damaging effects, has led far too many users to the destruction of opioids.”

The message — sent yesterday to all 100 Catholic schools and 288 parishes in the archdiocese — included a statement from the Massachusetts Catholic Conference, which includes all four Catholic bishops, published online Tuesday.

A total of 40,000 students are educated at local Catholic schools, according to the cardinal’s spokesman Terrence Donilon.

State Rep. Hannah Kane of Worcester, a member of the Campaign for a Safe and Healthy Massachusetts, said the group that advocates against Question 4 is “very grateful the message will be distributed.”

“Every effort to make sure voters are better informed of all the implications is helpful,” Kane said. “The people who will read that information that comes home will be the parents.”

Jim Borghesani of the group Yes on 4 said the legalization of marijuana would give opioid users a safer option, citing an August 2014 article in the Journal of the American Medical Association pointing to lower opioid overdose rates linked to state pot laws.

“I’m disappointed as a Catholic,” Borghesani said. “They came to their decision based on nothing but junk science and prohibition arguments. I think if they wanted to have a truly informed decision they would have reached out to us.”

A recent poll showed 53 percent of Bay Staters said they were in favor of the measure and 40 percent said they were not. Seven percent were unsure.

Despite the cardinal’s far reach, his message likely won’t change the outcome of the vote, said Fred Bayles, a Boston University professor and political messaging expert.

“I don’t think the influence of the archdiocese specifically or the Catholic Church in general has as much power as they once did,” Bayles said. “And I don’t think there’s anything in the Bible that says anything about marijuana.”