Omar Abdel-Rahman
It has to be noted that Shiraz Maher does specify that the major Salafi jihadist theorists like Abu Hamza al-Masri, Abu Muhammad al-Maqdisi, Omar Abdel-Rahman, and Abu Basir al-Tartusi ask to exercise caution while doing takfir, as declaring a Muslim unbeliever wrongly makes the one who accuses to himself get out of the religion of Islam and become an apostate himself.