Peter Tatchell has urged David Cameron to announce plans to reform Section 5 of the Public Order Act.
In the past the Act has been used by lawyers to prosecute homophobic religious preachers and gay rights campaigners.
The human rights activist took part in a demonstration outside parliament, organised by the Reform Section 5 campaign, towards the end of last week.
Drawing on his own experience of falling foul of the Act, while battling against homophobic religious clerics, Mr Tatchell said: “In 1994, I was prosecuted under Section 5 for displaying a placard that condemned the Islamist extremists of Hizb ut Tahrir.
“[They] had advocated the murder of LGBT people, and Islamist governments like Iran and Saudi Arabia have the death penalty for homosexuality.
“My placard read: ‘Islam Nazis behead & burn queers.”
Mr Tatchell argues it’s wrong to criminalises “insults” and that in a free society, people should be allowed to cause offense.
“If the criminalisation of insults was abolished, the rest of Section 5, which outlaws abusive and threatening words or behaviour, would remain in force. This is quite sufficient to protect vulnerable people and communities”.
“There have been too many abuses of this draconian law. Section 5 was invoked 18,000 times in 2009”.
“It has been used against a student who joked that a police horse was gay, a pensioner who said that religious beliefs were fairy stories, a street preacher who criticised homosexuality as immoral and a youth who condemned Scientology as a dangerous cult”.
Mr Tatchell claims the government is presiding over a “delay” when it comes to pushing ahead with reforms and adds: “the hesitation is unjustified”.
He also says the majority of MPs back a change in the law, along with the former director of public prosecutions, Lord Macdonald QC.
The Act has been the subject of a Home Office consultation.