Different Names - A Deviation!
Narrated Al-Harith Al-Ash'ari that the Messenger of Allah (ﷺ) said: The Prophet (ﷺ) said: "And I command you with five that Allah commanded me: Listening and obeying, Jihad, Hijrah, and the Jama'ah. For indeed whoever parts from the Jama'ah the measure of a hand-span, then he has cast off the yoke of Islam from his neck, unless he returns. And whoever calls with the call of Jahiliyyah then he is from the coals of Hell." A man said: "O Messenger of Allah! Even if he performs Salat and fasts?" So he (ﷺ) said: “Even if he performs Salat and fasts. So call with the call that Allah named you with: Muslims, believers, worshipers of Allah.”
Sunan Tirmidhi, Chapters on Parables, ﴾44﴿, hadith 2863. Classed as Hasan Sahih Gareeb by Imam Tirmidhi.
۩ Shaykh ibn Taymiyya said:
“Another case of sectarianism resulted over the Imams, causing people to classify each other in a way not ordered by Allah or His Messenger ﷺ. Like when someone is asked, “Are you Shukayki or Qarfandi?” These are false titles which Allah revealed no authority for. They are not found in the Book of Allah, the Sunnah of His Messenger ﷺ nor in the known reports from the salaf. So if a Muslim is asked a question lie this, then it is obligatory for him to answer, “I am neither Shukayki nor Qarfandi, rather I am a Muslim who follows the Book of Allah and the Sunnah of His Messenger.”
It is reported that Mu‘awiyah bin Abi Sufyaan asked Ibn ‘Abbaas radi-Allaahu anhu, “Do you follow the millah of ‘Ali or the millah of ‘Uthmaan?” He responded, “I do not follow the millah of ‘Ali, nor do I follow the millah of ‘Uthmaan. I follow the millah of Allah's Messenger ﷺ.” All of the salaf said that these names are deviation leading to the Fire. One of them said, “It is not clear to me which of these two favors are greater for me; that Allah guided me to Islam, or that He saved me from this deviation.” In the Qur'an, Allah ﷻ called us Muslims, believers, and servants of Allah (Abdullah). We do not equate the names which Allah has given to us to invented names which people call themselves and their forefathers, since Allah did not reveal any authority to do so.”
Al Wasiyat Al Kubra by Ibn Taymiyya, Page- 75.