The alarm was raised after a cleaner found damage to St Mary the Virgin Church on Thursday last week.
Thieves have stripped most of the lead from the 13th century roof overnight on Wednesday.
The vicar Rev Hilary Young, said she was shocked at the damage.
“It’s a despicable crime,” she said. “It’s the horror of seeing a building that has been there for a 1,000 years and is so precious to generations of people being treated this way.”
But she said the response from the community had been fantastic, with donations already coming in to help with the repairs. The church was also open for services on Sunday.
“I was very proud of our people,” she said. “There was an element of defiance.”
Contractors also turned up before the weekend to ensure the church was waterproof.
“We are hoping that it will keep the rain out long enough for us to get the money together to do a proper job”, said Rev Young.
The thieves, who it is believed were disturbed when neighbours called the police after they heard noises, also damaged four of the ancient embattlements on the roof.
The church was only insured for a small quantity of the theft because it didn’t have a roof alarm, and the church council now has to decide how to move forward.
The church was already fundraising to put toilets in the church and make it more comfortable. One of the options now facing the church is to join the fundraising together with the roof repairs and to set up a crowdfunding site.
“It is a challenge for anyone who is looking after these ancient buildings,” said Rev Young. “I would encourage anyone to put a roof alarm on.”
Cambridgeshire Police said: “We were called at 08:32 BST on Thursday to reports of a theft of lead from the roof of St Mary The Virgin Church in Gamlingay.
“Two vehicles containing lead were recovered nearby a short while later.”
The theft follows other incidents in the county with churches in Houghton Conquest and Stewkley also victims in recent weeks.
If you can help with fundraising you can email [email protected]
Anyone contacting that address will reach the church treasurer who can give information on donating to the cause, and also our crime number if anyone has information to give to the police on 101.