Militant cultural imperialists want Northern Ireland to become more Irish than the Republic of Ireland, a senior Orangeman said.
Demands for an Irish language act which have stymied political efforts to restore Stormont powersharing are part of a republican campaign to rid the country of its British identity, deputy grand master Harold Henning said.
He addressed Twelfth of July celebrations in Co Down on Wednesday.
"Sinn Féin want Northern Ireland to look and feel more Irish than the Republic of Ireland - and for our taxpayers to foot the bill.
"This militant cultural imperialism must be resisted by our elected representatives - whom we have just recently mandated to represent our interests and those of the Union."
Talks at Stormont have failed to produce devolved government following disagreement over a range of issues, including republicans' call for an Irish language act.
Part of the stumbling block surrounds reciprocal rights for Ulster-Scots speakers.
Mr Henning added: "Our politicians need to understand that we cannot support any development which would gift republicans an important victory in the cultural war.
"Let us ensure that what republicans failed to win with bomb and gun isn't now lost through their Trojan horse of equality and rights."
Sinn Féin has said its campaign is about honouring past political agreements and equality does not threaten anybody.
Mr Henning railed against the provision of Irish language schools for small numbers of pupils and the erection of road signs using Irish.
He said an Act which enshrines the Irish language in a legal framework will have massive implications for local government, the courts, the civil service, schools and everyday life.
"Language should threaten no one - however when language is used as a cultural weapon by political republicanism it clearly becomes a threat to our identity and community.
"Republicans have driven more people away from ever cultivating a genuine interest in Irish language than they will ever attract to it through their current radical proposals.
"The current demand for an Irish Language Act is simply the next chapter in the republican campaign to rid Northern Ireland of any semblance of British cultural identity."
POBAL, an independent advocacy organisation, has called for comprehensive legislation.
Its director Janet Muller said recently: "We have been very clear in the 11 years since the British government gave its commitment to introduce the Irish language Act that weak legislation would just increase frustration.
"We urge the political parties to stand firm in their support for rights-based legislation which can and will create a wide range of guaranteed rights in education, the political institutions, local authorities, administration of justice and media."