"Over the years the numbers have declined along with the rural population," he said.
"It's just a sign of the times, I guess."
Mr Grant's wife, Roz Grant, said Reverend David Hogg, who used to ride from Wanganui to Turakina on a bullock, writing his sermon notes as he went, would be attending the special service.
"The church will be open on Saturday afternoon from 12 to four, and there will be a talk on Turakina's history at two," she said.
On Sunday the church would be open from 10.30am, and Mr Grant would be dressed in a kilt to celebrate the church's Scottish roots.
Mrs Grant said she'd had people from Tauranga and Auckland indicate they'd like to come to the service, as they had ancestors who'd attended the church.
Mr Grant said it was about commemorating the fact that the building was 150 years old, and that it was one of the oldest buildings in the district that was still used for its original purpose.
He recalled "many happy times" in the church as a young boy, and said there was "lots of dedication to keep it going over such a long period".
There had been no resident minister for the church for the past 20 years, Mr Grant said, and retired ministers had been taking the services, which were held every second Sunday of the month, except January.
All are welcome to the church in the weekend, and anyone with questions can call the Grants on 06 327 3861.