The unbelieving infidels, who refuse to join Islam, must be killed, Koran 47:4: When ye encounter the infidels (unbelievers), strike off their heads till ye have made a great slaughter among them.
Every believing Muslim must join in this war again the unbelieving infidels, Koran 9:123. Believers! Wage war against such of the infidels as are your neighbours, and let them find you rigorous.
A war should be carried out again unbelievers and hypocrites, Koran 66:9: O Prophet! make war on the infidels and hypocrites, and deal rigorously with them.
Hell shall be their abode! Muslims must never stop fighting until there is no other religion left. Fight therefore against them until there be no more civil discord, and the only worship be that of God (Allah) (Koran 2:192).
Muhammad’s interpretation “When the Messenger of Allah (peace_be_upon_him) appointed anyone as leader of an army or detachment he would especially exhort him to fear Allah and to be good to the Muslims who were with him. He would say: Fight in the name of Allah and in the cause of Allah. Fight against those who do not believe in Allah. Wage a holy war” (Hadith, SAHIH MUSLIM 4294, the Hadiths are the teachings of Muhammad, the second most holy books).
Muslims must fight the infidels even if the infidels do not start the war: “The destruction of the sword is incurred by infidels, although they be not the first aggressors, as appears from various passages in the sacred writings which are generally received to this effect.” (AL-HEDAYA Vol. II, Hanafi Manual, Blackwell Idealist lawbase, reference number 3989) Muslims must wage war permanently, until the day of judgment: “The sacred injunction concerning war . . . It is established as a divine ordinance, by word of GOD, who has said, in the Koran, “SLAY THE INFIDELS; and also by a saying of the prophet, “war is permanently established until the day of judgement,” (meaning the ordinance respecting war.)” (AL-HEDAYA Vol. II, Hanafi Manual, Blackwell Idealist lawbase, reference number 3988). Muslims are allowed to kill other Muslims if it is essential to killing infidels: It is no objection to shooting arrows, or other missiles, against the infidels, that there may chance to be among them a Muslim in the way either of bondage or of traffic; because the shooting of arrow and so forth among the infidels remedies a general evil (AL-HEDAYA Vol. II, Hanafi Manual, Blackwell Idealist lawbase, reference number 3998). Muslims are allowed to kill children if it is essential to killing infidels: There is also neither fine nor expiation upon the warriors on account of such of their arrows or other missiles as happen to hit the children or the Muslims, because the war is in observance of a divine ordinance, and atonement is not due for any thing which may happen in the fulfilment of a divine ordinance, for otherwise men would neglect the fulfilment of the ordinance from an apprehension of becoming liable to atonement (AL-HEDAYA Vol. II, Hanafi Manual, Blackwell Idealist lawbase, reference number 3999).