More than 700 people have joined a Facebook group against a planning application to convert a disused building in Aiken Street into a place of worship and community centre.
Many of the messages on "No we do not want a mosque in Barton Hill" are from white people who claim they are being "pushed out" of their community.
Some are too offensive to be printed in a family newspaper, with claims that mosques are "breeding grounds for terrorists" and calls to vote BNP.
A number of messages of support are given by the far-right English Defence League, whose members were removed from Harbourside by police in riot gear shortly before the political leader's debate last week. Comments on the website have been branded as racist by other people who have posted in response to their views.
One referred to the commentators as "racist uneducated idiots", while another said "What's wrong with you lot? The world is changing, why can't you see that? People like you just make the English look like horrible people".
The proposal to convert the former Weston White factory into a mosque has been submitted to the council by Khalif Abdirahman, a parent governor at Barton Hill Primary School.
He hoped the mosque would help bring the community together and argued many of the messages from the site are from people outside of the area.
One post that supports his theory reads: "Even though I don't live in Somerset anymore, I don't want this! This is England! I have sent this to friends in the US too, invited 110 people and filled in the petition form to Bristol City Council."
Other comments included: "Why is there such a high demand for mosques ? Because in there [sic] twisted religion they believe all of the Earth is Allah's and they plan to dominate, no thanks **** off to the Middle East or some other Muslim hole."
Another said: "What can we do to stop this I live 2 mins away from it I don't want to walk up the street and fill [sic] like I am out numbered in my own country bring on the BNP."
Mr Abdirahman said he had taken his own petition around the area to canvass opinion and when the Evening Post spoke to people in Barton Hill, they were broadly supportive of the plans. The applicant said: "I took a petition and was amazed by how many supported it.
"We didn't go to the whole area but we had 100 signatures.
"It was a very positive reaction. One was from an 85-year-old white lady, that was very moving.
"The way I see it there are a few people, most coming from outside the area, who are doing it because of the election.
"It's not my job to respond to everything they say, it's my job to see that this project goes ahead.
It is in a secluded area, not adjacent to any houses, and will help the community engage."
Batook Pandya, director of Bristol Support Against Racist Incidents, condemned the racist comments but said people with genuine concerns should be listened to.
He said: "We all want controls on immigration but this is a community that has settled here and have a right to be able to feel safe and contribute to society.
"I don't believe the whole white Barton Hill community is racist, they are good, working class people. Hopefully the community centre will help remove fears and stereotypes, it is private property so it won't cost rate payers.
"I think people who do object on racist grounds should not be tolerated but if there are genuine objections, they should be addressed."
The protest site has echoes of a similar group that was set up when plans were submitted to North Somerset Council for a mosque in Weston-super-Mare. Although the plans were eventually rejected due to concerns about noise, planners had to discard 97 per cent of 157 letters of objection because they were racist.
The Barton Hill application, for external alterations and change of use for the former factory, is due to be heard by committee on a date to be set.
A Bristol City Council spokeswoman said: "The council will always discount abusive consultation responses whether or not they relate to planning applications.
"Comments on planning consultations must relate to relevant issues."
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