I pulled this definition from Wikipedia:
“Blasphemy in Islam is any irreverent behavior toward holy personages, religious artifacts, customs, and beliefs that Muslims revere. The Quran and the hadith do not speak about blasphemy. Jurists created the offence, and they made it part of Sharia. Where Sharia pertains, the penalties for blasphemy can include fines, imprisonment, flogging, amputation, hanging, or beheading. Muslim clerics may call for the punishment of an alleged blasphemer by issuing a fatwā.”
In other words, the death penalty is possible for this offense. And please note how Imams are the enforcement. This is one of the ways that Imams obtain power. Muqtada al-Sadr is a classic example of Imams wielding the power of a sovereign nation. He formed his own ‘army’ and is today a powerful figure in Iraq. Yet at the same time, he holds no political office.
Wikipedia goes on in its definition of Islamic blasphemy:
“The punishments for different instances of blasphemy in Islam vary by jurisdiction. A convicted blasphemer may, among other penalties, lose all legal rights. The loss of rights may cause a blasphemer's marriage to be dissolved, religious acts to be rendered worthless, and claims to property—including any inheritance—to be rendered void. Repentance may restore lost rights except for marital rights; lost marital rights are regained only by remarriage. Women have blasphemed and repented to end a marriage. Women may be permitted to repent, and may receive a lesser punishment than would befall a man who committed the same offense.”
Criticism of anything Islamic can easily (And frequently is) considered blasphemy. Just look at the potential power that this represents. That women can use this to end their marriage is only a relatively minor point. Blasphemy is one of the tools that Islam uses to subvert other legal system and cultures. Just look at the example of Judge Charles in New Jersey in 2009. This is where the war and violence enters the picture. Blasphemy of Islam is one of the causes of war and violence. Enforcement of Islamic blasphemy law IS enforcement of Islamic Sovereignty and one of the roots of Islamic nationalism.