Members at the World Peace and Unification Sanctuary in Newfoundland have been asked to attend the service with AR-15 semi-automatic rifle or equivalents such as an AK semi-automatic rifle.
An AR-15 was the weapon used by Nikolas Cruz when he opened fire at Marjory Stoneman Douglas High School in Parkland north of Miami on Valentine's Day, killing 17 people.
Tim Elder, the church's director of world missions, told Newswatch 16 that AR-15 rifles symbolise the "rod of iron" mentioned in the book of Revelation.
"Now more than ever, good people need to stand up and claim for themselves the tools that can be used to stop that kind of evil," he said.
The ceremony in Wayne County was planned before the mass shooting.
Elder said the church was not planning to reschedule or cancel the event.
Up to 600 people are expected to attend the ceremony next Wednesday.
"This will be a big thing for us. It's a new stage for us because it incorporates the rod of iron, as it is in Revelations," Elder added.
"Revelations talks about the returning Christ ruling with the rod of iron."
Wallenpaupack South Elementary School, which is located near to the church, is deciding what it will do in response to the ceremony.
Meanwhile, leaders of the National Rifle Association (NRA) are accusing supporters of gun control of exploiting the mass school shooting in Florida to promote an anti-gun agenda.
NRA leader Wayne LaPierre spoke at the Conservative Political Action Conference (CPAC). He said Democrats like House minority leader Nancy Pelosi of California and Connecticut senator Chris Murphy are eager to blame theNRA and are calling "for even more government control".
He said opponents of gun rights want to "sweep under the carpet" the failure of school safety, families "and even the unbelievable failure of the FBI" to prevent the shootings.
US President Donald Trump tweeted his backing of the NRA.
What many people don't understand, or don't want to understand, is that Wayne, Chris and the folks who work so hard at the @NRA are Great People and Great American Patriots. They love our Country and will do the right thing. MAKE AMERICA GREAT AGAIN!
— Donald J. Trump (@realDonaldTrump) February 22, 2018
Mr Trump said on Twitter: "What many people don't understand, or don't want to understand, is that Wayne, Chris and the folks who work so hard at the @NRA are Great People and Great American Patriots. They love our Country and will do the right thing. MAKE AMERICA GREAT AGAIN!"
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