Developer Bellway is seeking planning permission for up to 65 homes on land opposite Malling Abbey in West Malling, Kent.
The abbey, founded in around 1090, is home to a group of Benedictine nuns who have adopted a simple lifestyle with an emphasis on silent and isolated worship.
The community provides individuals with residential retreats and hosts heritage open days for schools.
Alongside its Grade I, II and II* listed buildings, the grounds are designated as an historic park and garden.
Opponents of Bellway's plans fear the construction and occupation of new homes will disrupt the community's peaceful existence.
Reverend David Green, vicar of St Mary's Church in West Malling, said the order of around 10 to 15 nuns, whose ages are estimated to range from 35 to 95, required a quiet environment to worship in.
"Their whole way of life is built around isolated prayer and peace and quiet," he said.
Bellway's plans would see fields on the eastern edge of West Malling occupied by a new estate.
Reverend Green said the side of the abbey grounds nearest the development housed the nuns' personal accommodation, cloisters, chapel and burial ground.
"They are there for a reason, it's the quietest part of the grounds," he said.
He added: "For the nuns, it's a particular concern because their entire way of life is built around silence and quiet, and they are being asked to effectively tolerate an enormous building site and a significant number of homes that will increase traffic and cause noise."
He said a section of the grounds was also rented to The Pilsdon Community, a Christian charity that provides refuge for the homeless, recovering alcohol and drug addicts and people fleeing domestic violence.
Reverend Green, a trustee to the charity, said up to 15 to 20 "vulnerable" people "who have nowhere to go" are supported in rebuilding their lives in the quiet community.
"Again, this development will be right on their doorstep," he said.
"If you flip it around, if this housing development had already been here, would Pilsdon, this charity, set up here? The answer is no.
"We all recognise there needs to be homes in the South East but they need to be in sensible places and, unfortunately, this is definitely not a sensible place."
Bellway originally sought outline planning permission from Tonbridge and Malling Borough Council for a development of up to 80 residential properties, reduced to 65 through amendments, including 40% affordable housing.
A public inquiry is due to start on August 20.
Trudy Dean, chair of West Malling Parish Council, said: "The whole community has come together to support the nuns against this highly-intrusive plan."
She claimed proposals would see around 80 metres of mature trees cut down for an access road, damaging the town's "rural character".
Mrs Dean, who also sits on Kent County Council and the borough council, said: "The effect on the abbey is devastating.
"If the sisters cannot carry on their work, we risk them quitting the site and losing what in many ways is the beating heart of our community, and has been for over 1,000 years."
West Malling Parish Council has set up an online crowdfunding webpage to raise £10,000 for legal support at the public inquiry to help protect the site "from the bulldozers".
A spokesman for the Newcastle-based, FTSE 250-listed Bellway said there was "a proven need for more new homes across Tonbridge and Malling", and that the development would "make an important contribution to the availability of private and affordable homes".
He added: "Only 35% of the site would be developed.
"The remaining area will be dedicated to creating open space for the benefit of the whole community.
"There would be a significant buffer of green space and landscaping separating the homes from the abbey and there are no plans to build along the boundary with the abbey.
"Bellway would contribute £550,000 in planning contributions towards primary and secondary schools, improvements to West Malling Group Practice doctors' surgery, local footpath improvements and other community uses."
A spokesman for the Diocese of Rochester, which owns the Abbey, said: "We do have concerns about the proposal and so are watching the work of the inquiry closely, and working with our agents on the matter."
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