The medival terms of Dar ul-Islam, Dar ul-Kufr and Dar ul-Harb are now irrelevant and inapplicable due to the new world order and the international covenants, constitution, peace treaties and relations. These terms were applicable during third and fourth centuries A.H.
The extremists’ theological justification of Killing Non-Muslims in Non-Muslim Countries and Leaving Their Homelands as Abodes of War (Dar al-Harb) to join ISIS is Untenable and Unfounded.
Thus, the fanatics believe that the people of these countries are not granted protection and that their lives and property are vulnerable and only may be protected by an Islamic battle (Ghazwa).
This can be refuted by clarifying that this classification made by Islamic jurists was not intended to exclude those Muslims living in non-Muslim lands from Islam. It is rather a classification that serves as a basis upon which rulings can be implemented, just like the classification of the globe into political territories.
The authentic Islamic position sets the criterion of whether a territory is the land where Muslims feel secure and safe to exercise their faith. Any such territory can be aptly counted as Darul Islam or An abode of Peace.
Imam Al-Kasani wrote:
“What is meant by designating the word “dar” (abode) with Islam and Kufr (disbelief) is not Islam and disbelief per se, but the state of security or insecurity. Moreover, the relative juristic rulings are not based on Islam itself or Kufr (in this case), but on the security or insecurity.”
Imam Ibn Qayyim Al-Jawziyyah states:
“This is the opinion held by the majority of scholars. It is crystal clear that Muslims jurists made their opinions according to Fiqh al-Ma’alat (Fiqh which considers the outcomes of actions).” Clearly, the practices of the extremist groups in the non-Muslim countries lead to accusing Islam of terrorism. Moreover, their actions are considered the most evil tools for defaming Islam in front of non-Muslims. If these groups are reasonable, they would realize that their actions work against Islam. They do not understand Muslim jurists’ views and, consequently, declare everyone residing in a non-Muslim country as a disbeliever.
In fact, Muslim jurists and scholars elaborated on the excellence of residing in non-Muslim countries since this may lead to guiding non-Muslims to Islam. Furthermore, the situation nowadays is very different as Muslims can freely perform their religious rituals. How do those people understand the hadith of the Prophet (PBUH):
“… and whosoever from my followers attacks other civilians (indiscriminately) killing the righteous and the wicked of them, sparing not (even) those staunch in faith and fulfilling not his obligation towards them who have been given a pledge (of security), is not from me (i.e. is not my follower)”. Ibn Qayyem Al-Jawziyyah, Ahkam Ahl Al-Dhimmah 2/873  Al-Muhallah 12/126. Moustafa Hamzah, ‘Ann Thaqafat Al-Erhab – Qiraah Shari’ah p.233.