Must a Muslim adhere to a specific madhhab if he believes in Allah and His Messenger and fulfills the pillars of Islam?

Denominations are divided into jurisprudential (fiqhi) and creedal (aqadi). As for the jurisprudential schools of the People of the Sunnah and the Community (Ahl al-Sunnah wal-Jamaah), such as the Hanafi, Maliki, Shafi'i, and Hanbali, there is no harm in attributing oneself to them and studying their jurisprudence, provided that one follows the correct proof from the Sunnah if it contradicts the madhhab. Attributing oneself to these madhhabs is neither obligatory nor recommended; what is required is adherence to the Qur'an and Sunnah and the guidance of the Companions.

As for creedal denominations, it is obligatory for a Muslim to be from the People of the Sunnah and the Community, those who follow the Qur'an and Sunnah with the understanding of the Salaf of the Ummah. Other groups, such as the Ash'aris and the Sufis, have deviations that contradict the People of the Sunnah.

Attributing oneself to a jurisprudential school or a dawah group that calls to the Qur'an and Sunnah is permissible, provided there is no loyalty or enmity based on it, and no fanaticism towards it, as this is an act of the people of Jahiliyyah. Imam al-Shafi'i said: "The Muslims are unanimous that whoever has had a Sunnah of the Messenger of Allah, peace and blessings be upon him, made clear to him, it is not permissible for him to abandon it for the saying of anyone." Sheikh al-Islam Ibn Taymiyyah mentioned that it is not permissible to set up a person for the Ummah whom one is loyal to and hostile to, other than the Prophet, peace and blessings be upon him, and that the foundation of the religion is the Qur'an and Sunnah. Therefore, it is not permissible for anyone to make his reference a person except the Messenger of Allah, or a speech except the Book of Allah. Whoever shows loyalty and enmity based on agreement with a person in word and deed is among those who have divided their religion.

Based on this, warning against the khatib for not following a specific madhhab is an error. Rather, his words and actions must be weighed against the Qur'an and Sunnah. If he is following them, then loyalty and assistance to him are obligatory.