Tasawwuf is a very general term and to this day remains undefined which has caused a lot of confusion. Due to its generality and vagueness the term has been outright rejected by the Salafis, and precisely due to its generality and vagueness, the Sufis are able to argue for its legitimacy.
[snip]
There also arose a different strand in Tasawwuf which was very philosophical in its approach. This tasawwuf was represented by people like al-Hallaj and Ibn ‘Arabi who philosophised tawassuf incorporating therein pantheism, the belief that the entire existence in reality is one existence, and that is the reality of Tawhid. It is this type of Tasawwuf which became widespread by the time of Ibn Taymiyya. Hence, not only Ibn Taymiyya but many other scholars from the four schools geared their efforts against this philosophical tasawwuf.
[snip]
Sh Muhammad b. ‘Abd al-Wahhab himself, along with his followers weren’t against tasawwuf as such. What they were against was the philosophical tasawwuf spearheaded by Ibn ‘Arabi and Ibn Farid.
The point is, since we know that tasawwuf is undefined, the modern day Sufis cannot use this term to legitimise their version of tasawwuf, which is firmly rooted in Shirk and bid’a of the very early pagans of Quraysh.
[snip]