“The One posited by these people has reality only in the mind, not in the external world.”
Thus, when the eternalist philosophers based (1) their doctrine on the claim that only one can proceed from the One, one of the first things demonstrating the falsity of their position was that the One about whom they made this claim has no reality outside the mind. Indeed, His existence there is impossible (2); He is merely conceived in the mind, just as all other impossibilities are conceived.
Likewise, when the Jahmiyya and the Muʿtazila—all of whom deny the divine attributes—affirmed a One who possesses no attributes whatsoever, the leading scholars who understood the true nature of their position held that their affirmation of divine oneness amounted merely to divesting Him of His attributes, which necessarily entails denying the Creator. Although they did affirm Him, they contradicted themselves by combining a position that necessarily denies Him with one that necessarily affirms Him.
For this reason, the leading scholars of Islam described them as negators of the divine attributes and as deceivers who affirm nothing and worship nothing, along with similar descriptions. Such statements are found in the words of more than one leading scholar of Islam, including ʿAbd al-ʿAzīz ibn al-Mājishūn (3), ʿAbd Allāh ibn al-Mubārak (4), and Hammād