What is the ruling on one who says that the most important thing in religion is Fiqh, and that Fiqh is only to be taken from the Sufis, and what is the stance to be taken toward him?

There is no need to discuss the importance of fiqh (understanding of Islamic law) in religion. It is a sign that Allah wills good for His servant, as the Prophet (peace and blessings be upon him) said: "Whomever Allah wishes good for, He grants him understanding in religion." Fiqh is to be acquired from its qualified, upright practitioners, as Imam Malik and Ibn Sirin said: "Indeed, this knowledge is religion, so be careful from whom you take your religion." It is not correct to limit the acquisition of knowledge to the Sufis, because the scholars of the Salaf (early generations) — from the Companions, their successors, and their successors' successors — who are the best of this Ummah, were not Sufis.