Lead thieves risked their lives by climbing a drainpipe in darkness to reach a rooftop around 60ft high at Spalding Parish Church.
The Vicar of Spalding, the Rev John Bennett, said the climb was at least the same height as two normal houses.
“There’s a hopper at the top and you have to climb over a parapet to reach the roof,” he said. “Just the thought of it scares the life out of me.”
The clergyman says church officials were lucky not to find someone lying on the ground after the raid.
The thieves got away with lead flashing, but left some lead rolled up on the roof because it was too heavy to lift.
All of the lead now has to be replaced.
Mr Bennett said: “They must have risked their lives in the dark to get up there, but even if they had managed to get the lead down to the ground, it is not worth much these days even if they could find a scrap metal merchant who would take it.”
The lead was marked with Smartwater and Mr Bennett says it would be easily identifiable if a scrap dealer checked.
Church officials know the drainpipe was climbed because wall brackets have shifted slightly.
Mr Bennett said: “The extraordinary thing is the risk they took climbing up the drainpipe in the dark.”
He said numbers of lead thefts at churches are falling.
The lead theft is the first at St Mary and St Nicolas for a number of years and happened on Tuesday or Wednesday night last week.