The Bishop of St Germans has issued a warning about the areas finances after figures showed congregations in Cornwall gave 20% less than other dioceses in England.
On average churchgoers in the area gave £5.80 a week compared to the national average of £8.40.
The Right Reverend Chris Goldsmith said: "If we continue to chase down declining income by reducing costs we risk an organisational death spiral from which it would be difficult to recover."
Bishop Chris said the church would be able to cope in 2015 but after that said "it would be irresponsible for the situation to continue."
The diocese has now started consulting the area's 12 deaneries about ways to tackle the problem.
The Bishop had previously warned that the diocese may be "under-investing in our churches and ministries".
He wants church goers to consider gift aid donations to bring in more money.
Chart shows annual budget for Diocese of Truro