Guernsey's Little Chapel has lost 90% of its income during the pandemic.
The foundation says it is because of a huge fall in the number of visitors from cruise ships - which have been cancelled until next year.
The Little Chapel usually attracts 70,000 visitors a year, but that figure has dramatically decreased during the pandemic.
The chairman John Silvester says this shortfall will affect their renovation plans as well as preparations for their centenary in 2023.
Before the pandemic hit, cruise ships to the island would contribute almost £4m to the local economy with more than 100,000 visitors every year. Guernsey's currently in Stage 3 of its exit from lockdown which still includes very strict quarantine requirements for anyone arriving in the Bailiwick. Last month, the States announced cruise ships would be cancelled until 2022.