He has twice written to Voluntary Sector Minister, Fiona Mactaggart, demanding that the draft Charities Bill stipulate that "an organisation must ensure equal opportunities in its employment policies and practices, and in its provision of services, to qualify as a charity".
But after two "insulting" responses to his letters, Tatchell said: "I will not accept the Home Office's wholly inadequate replies. It is astonishing that it believes that equal opportunities are unimportant and that it is happy to allow charities to discriminate."
Well known for his committed and direct campaigning on various issues, Tatchell said this campaign would continue once the draft Charities Bill is published for consultation and that he is working on gaining organisational support.
In his first letter, sent last December, he said it was not possible for organisations to act for the public benefit unless they have equal opportunities policies in place.
He said it is "unacceptable in a multicultural society, to privilege institutions that deny equality of opportunity", and that those charitable institutions that rejected it should be denied charitable status.
He added that the means by which a charity achieves its ends is as important as its goals. But the Home Office response disagreed. "The policies and practices a charity adopts to meet the needs of its service users are not among the criteria for judging public benefit and we do not believe they should be."
The reply stated that existing legislation that sanctions or penalises individuals responsible for failure of compliance, is sufficient. It added: "Removing charitable status would penalise the charity's service-users for the failings of its trustees and staff."
But Tatchell believes that by granting or continuing to give charitable status to organisations that are not equal opportunities employers would be wrong because "non-discrimination is an ethical imperative in a multicultural society".
His second letter, sent last month, said: "The reply seems to suggest that the ends justify the means. Good works and discrimination are incompatible."