Reference: Fataawa al-‘Aqeedah – Question 641, Page 597
Question: What is the limit, which if a person exceeds with respect to the religion, then it is considered extremism (ghuloo)? And what is the definition of extremism, and likewise the limit of negligence with respect to the religion?
Response: The limit, which if a person exceeds with respect to the religion, which is considered extremism is that which is in addition to what has been legislated; And extremism is [defined as]: “delving deeply into something and burdening oneself with it”.
The Prophet (sal-Allaahu ‘alayhi wa sallam) prohibited extremism, whereby he said:
«I warn you against extremism in the religion, for indeed those who came before you were destroyed as a result of extremism in the religion», transmitted by Ahmad and other than him with a sound chain of narration.
As for negligence [in the religion], then it is [defined as] “falling short in carrying out that which Allaah has made obligatory, by committing some sins such as adultery, backbiting, slandering or abandoning some of what has been made obligatory such as honouring the parents, maintaining the ties of the womb and returning the greeting and that which is similar [to these].”
And with Allaah lies all success and may Allaah send prayers and salutations upon our Prophet Muhammad (sal-Allaahu ‘alayhi wa sallam) and his family and his companions.