Editor's note: Frida Ghitis is a world affairs columnist for The Miami Herald and World Politics Review. A former CNN producer and correspondent, she is the author of "The End of Revolution: A Changing World in the Age of Live Television." Follow her on Twitter: @FridaGColumns.
(CNN) -- When a man with hands drenched in blood stands just feet away from the body of a person he just hacked to death, still holding the murder weapons, we want to believe he must be crazy. How else can our minds grasp the evidence that someone would carry out an act of such inconceivable brutality?
We don't yet know all the details surrounding Wednesday's killing in London. But the fact is we have seen this type of attack before, and even before one of the suspects started ranting to passers-by, we had a pretty good idea what to expect. This killing of a young British soldier was not an act of insanity. It was part of a pattern that has struck in many parts of the world before. This was the product of extreme Islamist radicalism we have all come to recognize.
Some will rush to blame Muslims or Islam for what happened, but it's important to be clear and not to mince words.
Islam is not the enemy. Muslims are not the enemy. Terrorism is not the enemy.
The enemy is the radical Islamist ideology that justifies any atrocity committed for political motives. The enemies are the people who promote this dogma and encourage others to engage in actions that offend and assault our humanity -- and theirs.
As information started trickling in from London, the familiar phrases started emerging, confirming our initial suspicions and no doubt disheartening Muslims who would like to see their religion stop having any association with these atrocities. Witnesses said they heard the two men shouting "Allahu Akbar" as they worked to dismember their victim. They say one of them breathlessly declared "By almighty Allah we will never stop fighting you until you leave us alone."
A similar attack happened a few years ago in Amsterdam. The Dutch filmmaker and columnist Theo van Gogh was assassinated and nearly decapitated by a Muslim radical angered by van Gogh's work criticizing Islam.
The London murderers apparently justified their butchery as resentment over Western troops fighting in Muslim lands. "Muslims are dying daily," the man with the bloody hands said. But before accepting that argument at face value, consider that radical Islamists have found other reasons to slaughter those who offend them. And the threshold for triggering brutality seems rather movable.
The Islamist radical who murdered van Gogh, Mohammed Bouyeri, used a knife to pin a letter to his victim's body, explaining his actions and threatening to kill Ayaan Hirsi Ali, an ex-Muslim and friend of the director, who remains a fierce critic of Islam. The letter is a screed against Jews and an attempt to intimidate anyone who speaks critically of Islam.
Islamist radicalism provided the twisted justification for the Boston Marathon bombings, for the videotaped decapitation of journalist Daniel Pearl, for the shooting rampage of Maj. Nidal Hassan, who killed 13 people in Fort Hood, Texas. And let's not forget 9/11, the crown jewel of murderous achievements.
Their political/religious ideology has motivated killers in Madrid, London, Jerusalem, Tel Aviv, as well as Syria, Nigeria, Indonesia and Iraq. The creed that demands murder, sometimes murder-suicide, for perceived offenses against Islam and against Muslims constitutes a threat to societies at large, not just to Westerners and non-Muslims. In fact, a study finds that Muslims are its most numerous victims.
While police were still working the crime scene in London, British Prime Minister David Cameron said the attack was probably an act of terrorism.
The question of whether this particular incident falls under the label of terrorism is not particularly useful. We will hear discussions about whether the perpetrators belonged to a larger organization or were, instead, "lone wolves" or "self-radicalized." In the end, the purpose was political intimidation, and inciting fear was its political objective. For what it's worth, that's terrorism. But that does not identify the enemy that must be fought.
The killing in broad daylight in London's Woolwich neighborhood belongs in the category of Islamist radical attacks, the same that brought 9/11, the Boko Haram massacres in Nigeria, restaurant bombings in Tel Aviv, night club killings in Bali, street explosions in Baghdad, hotel bombings in Amman and many other massacres in many countries. Each incident has its own peculiarities, its own list of grievances. But they all contain the same explosive ideology.
Most Muslims strongly oppose this kind of brutality. But a recent Pew poll showed significant minorities favor actions such as suicide bombings "in defense of Islam." A troubling 29% of Egyptian Muslims say suicide bombings can be justified, so do 40% of Muslims in the Palestinian Territories, 15% in Jordan and 18% in Malaysia.
The "defense of Islam" means different things to different people. Extremists have killed to defend Islam from modern westernized culture. They have killed women for daring to go to school. The victims often have nothing to do with the alleged offense. The Tsarnaev brothers' victims in Boston had nothing to do with the offenses that angered their killers.
An important element in the fight against this pernicious, callous enemy is a campaign to undermine the ideology's appeal within Muslim communities everywhere.
There is much work to do, particularly by the vast majority of Muslims who reject extremism, by their leaders who must be pressured by all of us to make the ironclad case that nothing, nothing in the world, justifies the kind of viciousness that assaulted our senses in London and has done so in too many places for too many years.
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The opinions expressed in this commentary are solely those of Frida Ghitis.