@Dr, Ahmed Makhdoom. The Holy Quran does not sanction the killing of those Muslims who are hypocrites and mischief makers but say that they will be the losers. The following verses from the Holy Quran are relevant:
2.8. And of mankind, there are some (hypocrites) who say: "We believe in Allah and the Last Day" while in fact they believe not.
2.9. They (think to) deceive Allah and those who believe, while they only deceive themselves, and perceive (it) not!
2.10. In their hearts is a disease (of doubt and hypocrisy) and Allah has increased their disease. A painful torment is theirs because they used to tell lies.
2.11. And when it is said to them: "Make not mischief on the earth," they say: "We are only peacemakers."
2.12. Verily! They are the ones who make mischief, but they perceive not.
2.13. And when it is said to them (hypocrites): "Believe as the people (followers of Muhammad Peace be upon him , Al-Ansarand Al-Muhajirun) have believed," they say: "Shall we believe as the fools have believed?" Verily, they are the fools, but they know not.
2.14. And when they meet those who believe, they say: "We believe," but when they are alone with their Shayatin (devils - polytheists, hypocrites, etc.), they say: "Truly, we are with you; verily, we were but mocking."
2.15. Allah mocks at them and gives them increase in their wrong-doings to wander blindly.
2.16. These are they who have purchased error for guidance, so their commerce was profitless. And they were not guided.
2.17. Their likeness is as the likeness of one who kindled a fire; then, when it lighted all around him, Allah took away their light and left them in darkness. (So) they could not see.
2.18. They are deaf, dumb, and blind, so they return not (to the Right Path).
2.19. Or like a rainstorm from the sky, wherein is darkness, thunder, and lightning. They thrust their fingers in their ears to keep out the stunning thunderclap for fear of death. But Allah ever encompasses the disbelievers (i.e. Allah will gather them all together).
2.20. The lightning almost snatches away their sight, whenever it flashes for them, they walk therein, and when darkness covers them, they stand still. And if Allah willed, He could have taken away their hearing and their sight. Certainly, Allah has power over all things.
2.21. O mankind! Worship your Lord (Allah), Who created you and those who were before you so that you may become Al-Muttaqun (the pious - see V.2:2).
2.22. Who has made the earth a resting place for you, and the sky as a canopy, and sent down water (rain) from the sky and brought forth therewith fruits as a provision for you. Then do not set up rivals unto Allah (in worship) while you know (that He Alone has the right to be worshipped).
2.23. And if you (Arab pagans, Jews, and Christians) are in doubt concerning that which We have sent down (i.e. the Qur'an) to Our slave (Muhammad Peace be upon him ), then produce a Surah (chapter) of the like thereof and call your witnesses (supporters and helpers) besides Allah, if you are truthful.
2.24. But if you do it not, and you can never do it, then fear the Fire (Hell) whose fuel is men and stones, prepared for the disbelievers.
2.25. And give glad tidings to those who believe and do righteous good deeds, that for them will be Gardens under which rivers flow (Paradise). Every time they will be provided with a fruit therefrom, they will say: "This is what we were provided with before," and they will be given things in resemblance (i.e. in the same form but different in taste) and they shall have therein Azwajun Mutahharatun (purified mates or wives), (having no menses, stools, urine, etc.) and they will abide therein forever.
2.26. Verily, Allah is not ashamed to set forth a parable even of a mosquito or so much more when it is bigger (or less when it is smaller) than it. And as for those who believe, they know that it is the Truth from their Lord, but as for those who disbelieve, they say: "What did Allah intend by this parable?" By it He misleads many, and many He guides thereby. And He misleads thereby only those who are Al-Fasiqun (the rebellious, disobedient to Allah).
2.27. Those who break Allah's Covenant after ratifying it, and sever what Allah has ordered to be joined (as regards Allah's Religion of Islamic Monotheism, and to practise its legal laws on the earth and also as regards keeping good relations with kith and kin ), and do mischief on earth, it is they who are the losers.