1. It is forbidden in Islam to issue fatwas without all the necessary learning requirements. Even then fatwas must follow Islamic legal theory as defined in the Classical texts. It is also forbidden to cite a portion of a verse from the Qur’an—or part of a verse—to derive a ruling without looking at everything that the Qur’an and Hadith teach related to that matter. In other words, there are strict subjective and objective prerequisites for fatwas , and one cannot ‘cherry-pick’ Qur’anic verses for legal arguments without considering the entire Qur’an and Hadith.
2. It is forbidden in Islam to issue legal rulings about anything without mastery of the Arabic language.
3. It is forbidden in Islam to oversimplify Shari’ah matters and ignore established Islamic sciences.
4. It is permissible in Islam [for scholars] to differ on any matter, except those fundamentals of religion that all Muslims must know.
5. It is forbidden in Islam to ignore the reality of contemporary times when deriving legal rulings.
6. It is forbidden in Islam to kill the innocent.
7. It is forbidden in Islam to kill emissaries, ambassadors, and diplomats; hence it is forbidden to kill journalists and aid workers.
8. Jihad in Islam is defensive war. It is not permissible without the right cause, the right purpose and without the right rules of conduct.
9. It is forbidden in Islam to declare people non-Muslim unless he (or she) openly declares disbelief.
10. It is forbidden in Islam to harm or mistreat—in any way—Christians or any ‘People of the Scripture’.
11. It is obligatory to consider Yazidis as People of the Scripture.
12. The re-introduction of slavery is forbidden in Islam. It was abolished by universal consensus.
13. It is forbidden in Islam to force people to convert.
14. It is forbidden in Islam to deny women their rights.
15. It is forbidden in Islam to deny children their rights.
16. It is forbidden in Islam to enact legal punishments (hudud ) without following the correct procedures that ensure justice and mercy.
17. It is forbidden in Islam to torture people.
18. It is forbidden in Islam to disfigure the dead.
19. It is forbidden in Islam to attribute evil acts to God ﷻ.
20. It is forbidden in Islam to destroy the graves and shrines of Prophets and Companions.
21. Armed insurrection is forbidden in Islam for any reason other than clear disbelief by the ruler and not allowing people to pray.
22. It is forbidden in Islam to declare a caliphate without consensus from all Muslims.
23. Loyalty to one’s nation is permissible in Islam.
24. After the death of the Prophet ﷺ, Islam does not require anyone to emigrate anywhere.
Found here. When you click through, you'll get to the main page. Click on "Read the letter." The first page is the summary quoted. Click on the right arrow in the upper left corner to turn pages and keep reading.
Each issue is elaborated, with quotes from the Qur'an and the Prophet, in the body of the document, where Muslim leadership from around the world calls Al Baghdadi out on all the various ways he's doing Islam wrong. I read the whole thing, and it's interesting to see what Muslim scholars say about all these issues, as opposed to the quick summaries, much less the slogans of fanatics we hear in the media.
This was originally written in September of '14, so I doubt Al Baghdadi is going to start paying any attention to it at this point. But it makes it clear (for anyone who still hasn't clued in) that the violent extremists who get so much play in the western media do not represent Islam as a whole, and that the scholars and leaders of Islam and Muslim people around the world don't approve at all of what ISIS and other groups and individuals with similar goals and methods are doing, in the name of a religion which does not support their actions.
Whenever you hear someone talk about how Muslims or Islam itself are inherently violent and hateful, this demonstrates just how wrong they are. Taking the acts of ISIS out on all Muslims is like blaming all Christians for what the KKK does.
Interesting stuff, especially if you don't know much about Islam. Talk half an hour or so and read it.