The Head of Scientology will visit Dublin tomorrow to open a new centre for the religion.
The building in Firhouse will include a conference centre with room for 1,100 people, but the census shows there are just 87 scientologists in Ireland.
Former scientologist, Pete Griffiths, does not believe that figure is accurate.
He said: "I actually don't think there is that many.
"I think some people just put that down as a joke, as people do sometimes on the census, they put down anything."
No one knows yet what the building will actually be used for, and that is causing some concern among locals.
Local county councillors were invited to see the new building, with many saying they will not go and one telling the organisers that he did not want to go in alone.
One local councillor, Dermot Looney, said on Twitter that he will have nothing to do with them and that he will monitor the situation to make sure no vulnerable people are targetted.
Just to confirm as I've been asked today;I won't be attending the Scientologists' opening in Firhouse & won't have anything to do with them— Dermot Looney (@dlooney) October 12, 2017
Like many people I have grave concerns about their practices, particularly recently around supposed drug rehab programmes— Dermot Looney (@dlooney) October 12, 2017
The Scientologists are not a banned organisation. They can purchase and use property as long as they're not in breach of planning rules— Dermot Looney (@dlooney) October 12, 2017
I am working with my colleague @CarlyBee25 to monitor the situation. We won't allow vulnerable people to be targeted.— Dermot Looney (@dlooney) October 12, 2017
Another local representative, Councillor Charlie O'Connor said:: "There is a lot of mystery around this, and I think that's unfortunate.
"I think the ball is now clearly in the court of the Scientology people to answer those question and just to repeat the phrase 'be good neighbours'."
The centre is due to open tomorrow, with protests expected.