The people of knowledge have explicitly mentioned that there is no objection in naming the people of division, pinpointing them and mentioning them with their characteristics in order to warn the people about their doubts, innovations and state/condition.
The following was said to Shaykh Muḥammad ibn ʿUmar Bāzmūl (حفظه الله): “There are those who say: ‘Have mercy upon Salafiyyah and do not be the cause of it’s division! So, [do not say] this one is Ḥaddādī and the other is this and the third is that, and so on.’ Hence, what is your opinion [on this]? May Allah preserve you.”
The Shaykh (حفظه الله) responded with the following: 
This speech contradicts the Ḥadīth of the Messenger (ﷺ); for indeed, the Messenger (ﷺ) mentioned that the Ummah would divide, and that it would divide into seventy-three sects, and he mentioned that all of them will be in the Fire except one. Hence, the Messenger (ﷺ) is the one who mentioned that there are sects and that all of them will enter into the Fire except one.
The scholars say, his (ﷺ) statement: “All of them are in the Fire except one,” is from the menacing texts, meaning, this is their punishment if Allāh pleases to punish them. They are under the will of Allāh. If He pleases He will forgive them, and if He pleases He will punish them.
Therefore, the Messenger (ﷺ) mentioned that there are sects, and they will amount to seventy three, and that this will occur in this Ummah. Hence, why do you disparage Salafiyyah and the Salafis in specifying/pinpointing the people of the [various] sects, the people of differing, and the people of the ḥizbī groups that are against and in opposition to the people of Islām [i.e. the Muslims].
When Shaykh Bakr ibn ʿAbdillāh Abū Zayd decided to write his book, Taṣnīf al-Nās Bayn al-Ẓan wa-al-Yaqīn [i.e. Classifying the People between Conjecture/Uncertainty and Certainty], he spoke to me before the book emerged, and there occurred between him and me a dispute/altercation. He mentioned to me that he was about to author a book with the title, Taṣnīf al-Nās Bayn al-Ẓan Wa-al-Yaqīn, so I said to him: “O Shaykh! The title of this book is not appropriate, since with this image, it seems as though you are disparaging the classification of the people, and the Messenger (ﷺ) said: ‘And my Ummah will divide into seventy-three sects.’” [Furthermore,] I said to him: “If you desire not to write except on this topic, be precise/meticulous.” [In addition to that,] I [also] mentioned to him the speech of al-Shāṭibī in al-I’tisām and others concerning the intricacies of these issues, since the people of knowledge have explicitly mentioned that there is no objection in naming the people of division, pinpointing them and mentioning them with their characteristics in order to warn the people about their doubts, innovations and state/condition.
Have you not seen the statement of ʿĀʾishah (رضي الله عنها) to the woman who asked her: “Does the menstruating woman do Qaḍaʾ [i.e. make up] of the ṣalaḥ?”?! She said: “Are you Ḥarūriyyah4?”  Therefore, did ʿĀʾishah (رضي الله عنها) intend to classify the people and to not be merciful to them?
[Furthermore,] when both of the Tābiʿīn came to Ibn ʿUmar (رضي الله عنهما) asking him about the people of Qadar, they called them the people of Qadar and Ibn ʿUmar accepted [that from] them, and he said to inform them that: “I am free from them,” the people of Qadar, [using] this name.
Therefore, there has come in the Aḥādīth and the narrations designation, naming and a description of the people of division and differing; hence, we walk upon this course, and we walk upon this path because it is the path of the believers. We say: The Messenger (ﷺ) informed us about this division and differing that has occurred in this Ummah and he (ﷺ) has named for us some of these sects. For example, he said: “The Khawārij are the dogs of the people of the Fire”;  hence, he called them Khawārij. [Likewise,] he said: “The Qadariyyah are the fire worshippers of this Ummah”;  hence, he called them Qadariyyah. So similarly, we name every one who ascribes to the people of division and differing, describe them, and pinpoint/identify them, if it were that warning from innovation and its people is not completed except through this. 
Therefore, there is no prohibition in this affair, and it is not from the chapter of dividing the people; rather, it is from the chapter of gathering/uniting the people upon the truth. Have you not seen that the Book [i.e. the Qurʾān], which was revealed in Islām!? Its name is al-Furqān [i.e. that which divides/splits], because it splits the truth from falsehood?! Have you not seen that the Messenger (ﷺ) was described as dividing a man and his father, a man and his brother, since he divided the people of īmān and the people of kufr?! So likewise, we differentiate between the people of the Sunnah and the people of innovation, and [likewise,] we differentiate between the people of division and differing [i.e. the people of the various deviated sects] and the people of union and harmony [i.e. the salafīs]. There does not entail in this the bringing about of ill/evil upon the people, nor does it entail their division. It simply entails the gathering/uniting of the people upon a common word.
: Sharḥ Uṣūl wa Ḍawābit fī-al-Takfīr pg. 280-282.
: Reported by Imām Aḥmad, Abū Dawūd, Ibn Mājah, al-Hākim and others, and Shaykh al-Albānī deemed it to be authentic in al-Ṣilsilah Aḥādīth al-Ṣaḥīḥah vol. 1, pg. 409.
: Reported by Imām Aḥmad, Abū Dawūd, Ibn Mājah, al-Tirmidhī, al-Hākim and others, and Shaykh al-Albānī deemed it to be authentic in al-Ṣilsilah Aḥādīth al-Ṣaḥīḥah vol. 1, pg. 402.
: That is, are you from the Khawārij? The term Ḥarūriyyah is an ascription to Ḥarūraʿ a place in Kūfah, al-ʿIrāq. The Khawārij are called this since the first group of them who revolted against ʿAli emerged from Ḥarūraʿ, and so they become popular with this ascription.
: Reported by Abū Dawūd and authenticated by Shaykh al-Albānī.
: Reported by Ibn Mājah and Ibn Abī ʿĀṣim in al-Sunnah, and Shaykh al-Albānī authenticated it in al-Sunnah vol. 2, pg. 438 and al-Mishkāt no. (3554).
: Reported by Imām Aḥmad and Abū Dawūd, and Shaykh al-Albānī deemed it authentic.
: What the Shaykh is saying is that warning from misguidance and innovation and their people is not accomplished and completed in full in some cases except by differentiating, classifying and identifying the various groups, naming and labelling them, and also descriibng them with their respective characteristics. Thus, if this is the case, then it is compulsory to do so since warning from misguidance and innovation and their people is compulsory, and whatever completes that which is compulsory is in itself compulsory. Therefore, differentiating, classifying and identifying the various groups, naming and labelling them, and also descriibng them with their respective characteristics by virtue of this is compulsory, because it completes that which is compulsory, and Allah knows best.
Translated by: Musa Shaleem Mohammed