And whoever kills a believer intentionally, his recompense is Hell to abide therein; and the Wrath and the Curse of Allah are upon him, and a great punishment is prepared for him. 4.93
(^^ the above matter is not one to be taken lightly, at all)
Guide us to the Straight Way.
The Way of those on whom You have bestowed Your Grace , not (the way) of those who earned Your Anger... 1-6
Killing any believers or killing yourself is a serious matter, and doing so results in Hellfire. Everyone must be careful, and stay away from extremism as the Companions of the Prophet (saw) fought against extremism (the Khawarij) and warned against it. These verses above are clear; Have no doubt about the Quran.
That is the Book there is no Doubt in it. A guidance for the God-Fearing.2.2
Remember that Uthmaan (Rda) was killed by muslims, who thought that they were doing the right thing.
Remember that Ali (Rda) was killed by a religious extremist.
Remember that Husayn (Rda) the grandson of the Messenger (saw) was killed by Muslims*
Know that the Khawarij are going to be around until 'Isa (Jesus Christ) Alayhisalaam comes back, and know that the Prophet (Saw) AND the Companions warned us strongly about them (about the Khawarij).
Protect yourself from the deviations that Shaytaan makes for Muslims.
And Allah knows best.
*=it was narrated that Zayd ibn Arqam said: The Messenger of Allaah (peace and blessings of Allaah be upon him) stood and addressed us at a watering place called Khumm, between Makkah and Madeenah. He praised and glorified Allaah, and he exhorted and reminded us, then he said: “O people, I am only human, and soon the messenger of my Lord will come to me and I will respond. I am leaving among you two weighty things, the first of which is the Book of Allaah in which is guidance and light. Follow the Book of Allaah and hold fast to it.” And he encouraged us to adhere to the Book of Allaah, then he said: “And the people of my household, I remind you of Allaah with regard to the people of my household, I remind you of Allaah with regard to the people of my household, I remind you of Allaah with regard to the people of my household.”
Narrated by Muslim (2408).
with regard to the family of the Messenger of Allaah (peace and blessings of Allaah be upon him) (Ahl al-Bayt), it is obligatory to love them, be loyal to them and respect their rights.
Majmoo’ al-Fataawa (28/491). From Shaykh Ibn Taymiyyah
for more about ahl-bayt see