Shaykh Salih al-Fawzan (hafidhahullaah) was asked the following question pertaining to aqidah (creed) and manhaj (methodology):

Is there a difference between aqidah and manhaj?

The Shaykh replied:

Manhaj is broader than aqidah, manhaj (methodology) occurs in aqidah, and in sulook (behaviour) and in akhlaaq (manners) and in mu'aamalaat (dealings), and in all the life of a Muslim. As for aqidah, then the foundation of eemaan (faith) is intended by it, and the meaning of the two testimonials and whatever is required by them both, this is aqidah.

Source: Al-Ajwibah al-Mufidah, p. 123 (3rd edition).

The Shaykh, just like other scholars (such as Shaykh al-Albaanee) explain a difference between aqidah and manhaj in terms of what they relate to (i.e. the subject matter), whilst affirming the inextricable link between aqidah and manhaj. This is very different to what is attempted by the biased partisans and Innovators who try to portray that so long as one's aqidah is sound, one can follow whatever manhaj he likes, and he will not be harmed. However, a Muslim is obligated to follow the Sharee'ah in everything, in all affairs, upon the way of the Salaf, without distinguishing between any of the affairs of the religion, and all the various aspects of the religion have methodologies that relate to them, that are founded upon the revealed texts, methodologies in deriving and understanding aqidah, methodologies in da'wah, methodologies in rectification, methodologies in fiqh and fataawaa and so on. So trying to separate manhaj from the affairs of aqidah and da'wah, or the religion in general is futile.