What is motivating the Islamic State (ISIS) to terrorise the world and commit the most brutal acts imaginable like killing hundreds of innocent civilians aboard a plane or in a concert hall?

Analysts have come up with an answer: The ISIS under the leadership of  Abu Bakr al-Baghdadi believes it's on a "divine mission" to draw "infidels" into Syria where it plans to wage an Armageddon-like battle which it believes it will win, the Washington Post reported.

To ISIS leader Abu Bakr al-Baghdadi and his cohorts, there is no such thing as brutality as seen through the "lens of Western rationality," the analysts believe.

"They don't see being way too brutal as a bad thing," Matthew Levitt, head of the counterterrorism programme at the Washington Institute for Near East Policy, tells The Washington Post.

"Brutality is working for them. They don't see taking over the world as overstretching. This is part of the divine mission."

The analysts say the ISIS downing of a Russian passenger aircraft on Oct. 31 killing all 224 people aboard and the massacre of at least 129 civilians in Paris last Friday were meant to anger Russia and the West and lure them to fight their envisioned final battle—Armageddon.

The more the West strikes in Syria, "it only builds into the narrative that the end is coming," according to Matthew Henman of IHS Jane's Terrorism and Insurgency Center, Newsmax reports.

The ISIS is telling the West and Russia, "you can carry out all these cowardly airstrikes in the air, but we'll come to your capital cities and we'll kill large numbers of your civilians on the ground. And you cannot stop us from doing it," Henman tells the Post.

The view is shared by William McCants, an analyst at the Brookings Institution and author of "The ISIS Apocalypse," who says the horrific attacks may be an ISIS decision to frighten France and Russia from further involvement in the Mideast — or an attempt to lure them further into the fight.

According to its online propaganda magazine, "Dabiq," the ISIS believes that it will eventually emerge victorious in the war against the infidels, culminating in a final end-of-days battle in Dabiq, near the northern city of Aleppo.

The Washington Post notes that in each edition of the ISIS magazine features the same prophetic quote about how things will unfold: "The spark has been lit here in Iraq, and its heat will continue to intensify — by Allah's permission — until it burns the crusader armies in Dabiq."

U.S. officials, including CIA Director John Brennan, have a different view on why the ISIS is extending its attacks abroad. Brennan believes that the group's loss of territory in Syria and Iraq due to battlefield defeats has undermined the ISIS legitimacy, prompting its leadership to show their power in other ways.

"It has not had that type of momentum inside of those two countries," Brennan said in a speech at the Center for Strategic and International Studies, the Post reports. "Which is why I think they are looking abroad now to have these spectacular attacks."

Daniel Byman, a Georgetown University professor and terrorism expert, has another view. He tells the Post that the attacks were meant to encourage more Muslims to join ISIS.

"If you are a young Muslim who is angered by the attacks on Sunnis in Syria, this is a group that is showing it's fighting back by hitting [your] enemies," he says.