It's common to come across people who believe that ISIS follows Quran to the letter.  Their argument is normally as follows:

"ISIS follows the same book that muslims follow. Chapter 9 of the Koran is very clear on the culmination of Mohammed's  message. Verse 5 - "Slay the infidels where you find them", verse 111 - "You were made to slay and be slain for Allah". Ofcourse muslims claim that that passage is only for war and therefore not relevant. Well, we can't ignore that almost 100% of religious violence is committed by muslims. There are entire channels on YouTube by ex-muslims where they go over the persecution they have faced from their own community for leaving Islam. We all know how Asiya Bibi was dragged through the streets while being beaten by a muslim mob for allegedly criticising Mohamed. A religion with no freedom of thought and no freedom of expression is not compatible with any free society. Just the way ex-muslims are treated by the muslim community shows the hatred that is there in Islam for anyone who is not muslim. ISIS follows chapter 9 of the koran to the letter."

My response is:

It's obvious that the writer is coping from others and its obvious that the writer hasn't read Quran.

It's also obvious that those whom the writer is copying from are deliberately hiding parts of Quran that they don't like. For example, in this case,  9:11 that is being qouted also says:

"They fight in the cause of Allah, so they kill and are killed. [It is] a true promise [binding] upon Him in the Torah and the Gospel and the Qur'an."

Obviously,  those who refer to 9:5 don't want the reader to know that Quran's stand in this case is similar to that of Torah (Jewish holy book) and the Gospel (Christian holy book).

Now, it's TRUE that 9:5 asks muslims to specifically fight the polytheists who broke their oath. Its Quran that explains that, not muslims. Lets examine this by referring only to verses from chapter 9.

9:10 says:

"They do not observe toward a believer any pact of kinship or covenant of protection. And it is they who are the transgressors."

9:13 says:

"Would you not fight a people who broke their oaths and determined to expel the Messenger, and they had begun [the attack upon] you the first time?"

Its obvious that muslims are being asked to fight the polytheists who refuse to live and let muslims live.

Chapter 9 goes on exempting and sparing the polytheists who respect their treaty with muslims, don't support an enemy of muslims and even those polytheists who are ignorant:

9:4 says:

"Excepted are those with whom you made a treaty among the polytheists and then they have not been deficient toward you in anything or supported anyone against you; so complete for them their treaty until their term [has ended]. Indeed, Allah loves the righteous [who fear Him]."

9:6 exempts the ignorant:

"And if any one of the polytheists seeks your protection, then grant him protection so that he may hear the words of Allah . Then deliver him to his place of safety. That is because they are a people who do not know."

9:7 says:

"So as long as they are upright toward you, be upright toward them. Indeed, Allah loves the righteous"

Conclusion:

ISIS doesn't follow Quran. ISIS is a politically infiltrated group followed by the over ambitious, damaged and foolish in mind muslims.

The culmination of Mohamed's message is beautifully summarized in chapter 22 verse 40:

"They are] those who have been evicted from their homes without right - only because they say, "Our Lord is Allah ." And were it not that Allah checks the people, some by means of others, there would have been demolished monasteries, churches, synagogues, and mosques in which the name of Allah is much mentioned. And Allah will surely support those who support Him. Indeed, Allah is Powerful and Exalted in Might."