I can't help but roll my eyes when I'm informed I must keep a guard with me at all times now. After my father, Salmaan Taseer, was assassinated by his own security guard on 4 January – my brother Shehryar's 25th birthday – does it even matter? If the governor of Pakistan's largest province can be shot dead by a policeman assigned to protect him in broad daylight in a market in the federal capital, Islamabad, is anyone really safe?

It was after lunch that I started receiving one message after another from friends inquiring about my father. I rang him. No answer. I called his chauffeur in Islamabad. He was wailing and incoherent. I told him to calm down and tell me everything. The governor had been about to step into the car after lunch at his favourite local cafe, he said. He had been shot in the back. There was a lot of blood, he said. I told him everything would be fine: my father was a fighter and he would make it.

According to the postmortem report I read, they recovered 27 bullets from his body, which means the gunman actually reloaded his weapon so nothing would be left to chance. Each one of my father's vital organs was punctured by the hail of bullets, except his heart and larynx – his mighty, compassionate heart and his husky, sensible voice.

The assassin, Mumtaz Qadri, had reportedly asked others in the governor's temporary security detail to take him alive. Almost a dozen, including security personnel, are now under arrest. Speaking to camera crews the same day from jail, 26-year-old Qadri said he had killed my father because he had criticised the country's draconian and often misused blasphemy laws. It seems that Qadri was also inspired by the rally against my father on 31 December, at which rabid protesters demanded his blood. Yet no arrests were made over this brazen incitement to murder.

The blasphemy laws were foisted on Pakistan by Islamist dictator General Zia-ul-Haq in the 1980s. As an intellectual firebrand of the Pakistan People's Party, my father endured jail and torture during that dictatorship. We had thought the nightmare and brutality of the Zia regime was over when the general's aircraft fell out of the skies in 1988. We were so wrong.

Some 200 lawyers – men of the law – garlanded Qadri and showered him with pink rose petals on both his days in court. The president of the lawyers' wing of the opposition party Pakistan Muslim League-Nawaz was reportedly among them. The smiling assassin has become the poster boy for the unholy ambitions of the self-deluded. Lawyers who fought for an independent judiciary are standing in support of a self-confessed murderer. This is not the Pakistan for which my grandfather, MD Taseer, fought alongside founding father Mohammad Ali Jinnah.

The inability of the state to prosecute terrorists successfully is proving fatal for Pakistan. The country's antiterrorism courts, where Qadri was presented, have a sorry record on convictions, and have been clogged by non-terrorism cases. The state is unable to gather evidence properly, make a cohesive case and ensure the safety of those who provide evidence against the militants. It is a different matter when it comes to trying poor, underprivileged Pakistanis – Muslims and non-Muslims alike – accused of blasphemy. Under pressure from the mobs outside, Pakistan's lower-level courts convict quickly, but these convictions are almost always overturned by the higher judiciary, although the accused (and in some cases the judges) are then killed by vigilantes.

My father was buried in Lahore on 5 January under high security. Cleric after cleric refused to lead his funeral prayers – as they had those of the sufi saint Bulleh Shah – and militants warned mourners to attend at their own peril. But thousands came to Governor House on that bitterly cold morning to pay their respects. Thousands more led candle-lit vigils across the country. But the battle is not going to be over any time soon.

In Pakistan, the voices calling for reason and tolerance are in danger of being wiped out. The fear is palpable. The militants have issued a warning against further vigils for my father. Yesterday, a rally in support of the blasphemy laws was held in Karachi, at which mullahs incited violence against former information minister Sherry Rehman – my mother's close friend, and the brave woman I was named after – who tabled a bill in the National Assembly in November proposing blasphemy-law amendments. The politician and former cricketer, Imran Khan, and former prime minister Chaudhry Shujaat Hussain – both conservatives – have also come out in support of my father's position: amending the blasphemy laws to prevent their misuse. The ruling party – my father's party – continues to equivocate.

My father's assassination was a hate crime fuelled by jihadist fervour, abetted by some irresponsible sections of the media and sanctified by some political actors. All that is necessary for the triumph of evil is that good people do nothing. The loss of one good man must not deter others. Pakistan's very future depends on it.