This is mainstream Islam. And it's horrifying.
You know that part in the video where the announcer is speaking over the Muslim killer. That's the part where the killer is saying, "Many, many Ayah throughout the Koran that we must fight them as they fight us." Instead the official media video cuts the Koran part out and picks up only when the Muslim killer says, "An eye for an eye and a tooth for a tooth."
That doctrine is used today by Muslim countries to demand a literal eye for an eye justice.
In August 2000, the Saudi Arabian media reported that Abdel Moti Abdel Rahman Mohammad, a 37-year-old-Egyptian national was subjected to forcible surgical removal of his left eye at King Fahd Hospital in Medina. The operation was carried out as a judicial punishment of Qisas after he was found guilty of disfiguring Shahata Ajami Mahmoud, a 53-year-old Egyptian.
So it's not some sort of misunderstanding. This is mainstream Islam. And it's horrifying.
But there is a larger context. The Koran, as usual, is blasting the Jews for not keeping the law of Allah, which Mohammed believed, actually involved taking out an eye for an eye. The Jews never practiced this. Mohammed however insisted on it and laid out proper doctrine.
"The reward of those who wage war against Allah and His Messenger and strive to create disorder in the land is only this that they be slain or crucified or their hands and their feet be cut off on alternate sides, or they be expelled from the land." (Quran 5:34)
"And as for the man who steals and the woman who steals, cut off their hands in retribution of their offense as an exemplary punishment from Allah. And Allah is Mighty, Wise." (Quran 5:39)
And whoso judges not by that which Allah has sent down, these it is who are the disbelievers. (Quran 5:45)
And therein We prescribed for them: A life for a life, and an eye for an eye, and a nose for a nose, and an ear for an ear, and a tooth for a tooth, and for other injuries equitable retaliation. And whoso waives the right thereto, it shall be an expiation for his sins; and whoso judges not by what Allah has sent down, these it is who are wrongdoers. (Quran 5:46)
And let the People of the Gospel (Christians) judge according to what Allah has revealed therein, and whoso judges not by what Allah has revealed, these it is who are the rebellious. (Quran 5:48)
O ye who believe! take not the Jews and the Christians for friends. They are friends one to another. And whoso among you takes them for friends is indeed one of them. Verily, Allah guides not the unjust people. (Quran 5:52)
The Muslim killers likely thought of themselves as delivering "judgement" on an England which refused to follow the will of Allah.
To Muslims, the beheading and disemboweling they visited on an English soldier was an expression of the law of Allah. By carrying it out they were not just committing an act of terror, but calling the English to Islam by showing them the glory of the "True Way".
UPDATE: Robert Spencer has more details of the Koranic inspiration for this atrocity.
He says, "Surat at-Tawba through...many, many ayat throughout the Qur'an that...we must fight them as they fight us..."
Surat at-Tawba is the ninth chapter of the Qur'an, and according to Islamic scholars is the last one or one of the last ones to have been revealed that contain doctrinal content -- which means that it takes precedence over the others. Some highlights:
"And when the sacred months have passed, then kill the polytheists wherever you find them and capture them and besiege them and sit in wait for them at every place of ambush. But if they should repent, establish prayer, and give zakah, let them [go] on their way. Indeed, Allah is Forgiving and Merciful." -- 9:5
"Fight them; Allah will punish them by your hands and will disgrace them and give you victory over them and satisfy the breasts of a believing people and remove the fury in the believers' hearts. And Allah turns in forgiveness to whom He wills; and Allah is Knowing and Wise." -- 9:14-15
"Fight those who do not believe in Allah or in the Last Day and who do not consider unlawful what Allah and His Messenger have made unlawful and who do not adopt the religion of truth from those who were given the Scripture - [fight] until they give the jizyah willingly while they are humbled." -- 9:29
"O Prophet, fight against the disbelievers and the hypocrites and be harsh upon them. And their refuge is Hell, and wretched is the destination." -- 9:73
"O you who have believed, fight those adjacent to you of the disbelievers and let them find in you harshness. And know that Allah is with the righteous." -- 9:123