And what is the ruling in Islamic law regarding one who says: "Allah is merely existent," and is content with the word

The Shaykh : The opposite of this is error, and indeed misguidance, which is to satisfy the Muslim by saying, as came in the question: "Allah is merely existent." He says: "Allah is existent." This is not sufficient, because such general speech is shared by all the people and followers of religions, whether they are safe from alteration and change, like Islam, or those upon which distortion and change have befallen, as is the case with Judaism and Christianity and other religions that have perished or nearly perished completely. It is not permissible for the Muslim to be satisfied by saying: "Allah is existent" and then nothing beyond that. Why? Because Allah (Mighty and Majestic) is described with every attribute of perfection and free from every attribute of deficiency, as He (Mighty and Majestic) said: If Allah (Mighty and Majestic) says: then in this text there is negation and affirmation. In this verse there is negation and affirmation. The negation is a purification of Allah, and the affirmation is an honor for Allah (Mighty and Majestic) by describing Him with what befits Him of attributes of perfection: .
So the one who is satisfied by saying: "Allah is existent, and that is all," means that he believes in an essence whose attributes are unknown in his mind and in his creed. And this means that he is turning away from the guidance of the Noble Qur'an which Allah (Mighty and Majestic) revealed upon the heart of Muhammad (peace and blessings be upon him). If that one who is satisfied with his saying: "Allah is existent, and that is all," adds to his saying by saying: "No, I believe that Allah is an essence and He has attributes of perfection." We say to him: This is a return and a going back to the truth, and perhaps it is the complete truth. At that time, it is incumbent upon this Muslim who says: "I believe that Allah is existent, and more than that, He is described with everything by which He described Himself in the Book or in the authentic Sunnah." If that speaker says this word, he is in general—in general, and not yet in detail—on the right path and on guidance from his Lord. But this correctness is not completed except by adding to this general belief the detailing of this generality by believing in everything that his knowledge encompasses of the divine attributes that were mentioned, as we said, in the Book and in the Sunnah. This is necessary for every Muslim to have his creed established upon this initial generality and then upon this detail, which also requires detailing. And the matter, as I feel, bears a wide and very wide explanation, but I do not want to go far from the basic answer to this question. So when I said in the introduction to the answer, the summary of which is: that place is derived from creation, and that it is created from the creation of Allah, and that it is not permissible to place Allah in His creation, meaning: that we do not speak of what has not come in the Sunnah.