Shaykh Ahmad an-Najmee stated:

However, what is correct beyond any doubt is that these young people, those who declare Muslims as being disbelievers, they've taken this methodology, the methodology of Takfi (excommunication), as well as substantiation for their bombings from none other than the methodology of The Muslim Brotherhood, al-Ikhwan al-Muslimeen. They've adopted it as the essence (of their way), their patterns, their training, their cultivation and upbringing, and means of their incitement and motivation.

They deceptively incite and claim that committing such crimes (Takfir and bombings) are forms of Jihad supported and encouraged by the Quran! And they take that from the books of Sayyid Qutb (d. 1966), the man who made Takfeer of the entire nation of Muhammad (sallallaahu alayhi wasallam) as ismentioned in his Quranic explanation, Fi Dhilaal il-Qur'aan (In the Shade of the Quran) vol. 4, pg. 2122, when he says, There is not on the face of the earth today a Muslim country or even a Muslim community with social principles based on Allah's legislation or on Islamic understanding. He also said similar things in his explanation of Surah Yunus. He even claimed that Muslim mosques are really temples and places of idol worship. He encouraged political revolutions and overthrows in his explanation of Skrah al-Anfal,alleging that Islam allows and commands it. He says in his explanation of Skrah al-An'aam vol. 2, pg. 1057:

The times have always revolved, since the day this religion came to mankind, around "There's none worthy of worship but Allah." But humanity has become apostates back to the worship of the servants (themselves) and to the injustice of other religions. They've become renegades, leaving "There's none worthy of worship but Allah." even though a portion of them may still verbally repeat "There's none worthy of worship but Allah." without even realizing its meaning.

A group of bombers that appeared on Saudi television even confessed and stated they've taken the idea of Takfeer from Sayyid Qutb's books, specifically from In the Shade of the Quran. In this is a refutation against those who say that what leads these people to do their crimes is unemployment or other things.

I've read in the book, Caravan of the Muslim Brotherhood by Abbaas as-Seesee - the first volume - lots of incidents showing that members of the Muslim Brotherhood were raised on a terrorist ideology since their beginning. Read, for example, vol. 1, pg. 258 about how Judge Ahmad Bak al-Khazindar was murdered by the Muslim Brotherhood. All these things are mentioned at the end of the first volume of Caravan of the Muslim Brotherhood by Abbaas as-Seesee, one of those who've adopted and profess this methodology. His book is a compilation of such incidents, a confession to them. All these things and more occurred during the life of Hassan al-Banna (founder of the Muslim Brotherhood) between 1947-1948. Is this not evidence enough that the Muslim Brotherhood is nothing more than a Takfirist sect, using methods of harshness, violence, and bombings? It's the same terrorism referred to in present times.

I wrote this to clarify that the people who say that takfir and bombings are the results of unemployment, or learned from Muhammad Ibn 'Abd al-Wahhab, or from the book, al-Durar al-Sinniyyah - all these allegations are false. Only the biased, sectarian factionalists of this same sect make such claims or those who sympathize with them. Hopefully with this clarification, their lie is made known as is the deception of those responsible for trying to cover up the actual cause leading to that (bombings and destruction). With Allah lies all success. May peace be on our prophet Muhammad, his family and companions.

- Ahmad Ibn Yahya Ibn Muhammad Ibn Shabir al-Najmi
7/14/1425 Hijrah (C.E. 8/30/2004)

Source: Answering-Extremism.Com