Salam (1926-96) was born in Jhang, Punjab, in British India. The 1947 partition of India made Salam a Pakistani. His family belonged to the Ahmadiyya sect in Islam founded by Mirza Ghulam Ahmad (1835-1908), an autodidact scholar of Arabic and Persian, who claimed to be a messiah or renovator of faith in 1889. The followers of Ahmad grew in number during the British Raj despite the fierce opposition of orthodox Muslims. Their circumstances, however, changed for the worse following India's partition.
During Pakistan's early years Ahmadis experienced hostility, yet the government remained neutral and protective of them. This changed in the 1970s when Ali Bhutto's government under Saudi Arabia's influence declared the Ahmadiyya sect to be outside of Islam, and formally branded Ahmadis as non-Muslims. Since then Ahmadis have faced persecution as apostates and blasphemers in Pakistan, Saudi Arabia and wherever in the Muslim world the Wahhabi version of Saudi Islam finds favour among people, as in Afghanistan.
Like I said, such religious persecution happens in almost every religion and beliefs over different times. It is sad that such an outstanding person is being totally ignored. It is not as if he's a murderer, or did some heinous crime.