Islamic State of Iraq and Syria, now simple the Islamic state, executed 13 leading Sunni clerics last month. The leaders were executed for refusal to pledge loyalty to the Islamic State.
These executions are evidence that ISIS is cracking down on dissent, and will refuse to allow any contradictory opinions in what it regards as its territory.
Heiner Bielefeldt, the UN's special rapporteur on freedom of religion or belief expressed serious concern about the turn of events. "Here a Sunni movement is executing Sunni religious leaders. That should make us think." she said. "It's important to focus more attention on these particular killings, because here we are not talking about Sunnis versus [Shiites]. This is a very clear case of atrocities committed against their own people, against religious leaders from Sunni Islam who probably have a less simplistic understanding of what Islam means."
ISIS claims to have executed 1,700 captured Shiite Iraqi soldiers. They have posted videos online of executions they have performed. On previous occasions they have publically displayed the crucified bodies of their enemies.
Their reputation for brutality serves as propaganda tool that ISIS uses to demand obedience.
One of the Sunni clerics executed by ISIS was the former Imam of Mosul's famous Nur-al-din Mosque. Abu Bakr al-Baghdadi used that Mosque as the location for his first public appearance on Friday. He used the occasion to deliver a sermon, calling for loyalty from all Muslims, and exhorting all believers to fights jihad.
"This month (Ramadan) is the month for Jihad" he declared. "When the prophet made armies to fight the enemies of God, the month where he would wage Jihad on polytheists! So take advantage of this month and obey Allah."
ISIS is now controlling the content of all friday sermons delivered in Mosul.
Since their initial sweeping advances, the biggest Islamist victory since 9/11, ISIS seems to have most of their energies into consolidating their gains. Most of the fighting at the moment is concentrated around the Iraqi city of Tikrit, which the Iraqi army is currently attempting to reconquer.
One indication of their will to stay was the announcement of the creation of a new Islamic Caliphate on June 29th, the first day of the Muslim holy month of Ramadan. According to Islamic extremists, Ramadan is the optimal time of the year for Jihad.
At the same time as ruthlessly crushing dissent, ISIS is also engaged in attempting to draw people into its cause. ISIS' gains in Iraq would not have been possible without the aid of Sunni tribal fighters, who bitterly resent President Nouri al-Maliki and his Shiite government.
Sheikh Raad Abdul Sattar Suleiman, a spokesman for the Tribal Revolutionaries coalition also heads their Coalition Committee. He is a senior member of the Dulaim tribe, which has 3 million members in Iraq. told reporters that there was cooperation between ISIS and Sunni tribal militia groups, although tribal readers did not recognize the Caliphate yet. However, he opened the door to that possibility in the future, saying: "If ISIS liberates Iraq and expels the Iranians who are backing the Maliki government, we will give it our blessing and support its Islamic State. The important thing is to save Iraq from the Iranians"