*Islam does not permit killing of a person based upon his or her beleifs. *
Actually, you'll find that it does but only for the State to do the killing in very specific cases:
examples I can think of are:
1) The Islamic punishment for apostasy if proven is death.
2)Any one who insults the Beloved Messenger of Allah sal Allahu alayhi wa sallam is to be killed. His tawba will not be accepted. See al-
Shifa of Qadi Ayaad: Chapter: The Punishment for those who insult the Messenger of Allah.
3) During Hazrat Ali's khilaafat mubaarak a group of people had the kufr beliefs that, nauzubillah, Hazrat Ali was God incarnate!
When Hazrat Ali found out about them he ordered them to be burnt alive. This is an historic fact.
4) Hazrat Umar had an Imaam put to death during his khilaafat because the man was denigrating The Beloved Prophet sal Allahu alayhi wa sallam.
5) Hazrat Abu Bakr's reign is famous for the Wars of Ridda [Apostasy].
6) Sultan Salaah ud Deen al Ayyubi of the Crusades fame had a certain Rafidi philosopher killed for his beliefs.
Actually, for the kaafirs they will be in eternal torment for their BELIEFS no matter how many good things they might have done on earth.
The first question is going to be about aqeedah before anything else.
There's no denying that the Qadianis are going to be in the deepest part of the Fire for denying the Finality of Rasool Allah's Prophethood and for other countless blasphemies. They will be right there alongside Firaoon and Dajjal and Abu Jahl and Musaylama al KaDhaab and all those others who thought they were prophets along with their followers.
If a murtad dies he/she is not to be buried in an Islamic cemetery; rather that person's body is to be burnt, flung into a ditch and the ditch covered with rocks lest the foul stench of his corpse be emitted. This is the Islamic ruling for the murtads.
Note that I'm not saying that all qadianis in pakistan or elsewhere should be killed but I am saying they should not be allowed to call themselves Muslims nor should they have the same rights as Muslims and if they do then they must be faced with the Law.
Ideally, I wish Allah would get rid of all of them in an instant. Insha Allah when Imam Mahdi comes he will clear the world of such kuffaar.
JazakumAllah Khair for correcting me brother Asif. Actually I was speaking in context of the revenge killings that were being so hotly debated. Yes indeed such punishment must be implemented on caliphate level. As far as these revenge killings are concerned, I am not sure about the verdict of our Ulema regarding them. Perhaps you would oblige us by sharing what you might know in this regard.