What is the interpretation of the verse: (He is the First and the Last, and the Outward and the Inward), and is its interpretation as unity of existence correct? And what is the interpretation of the phrase "there is no god but Allah", and is "there is no existent but Allah" among its meanings?

The doctrine of "Wahdat al-Wujud" (unity of existence) is disbelief and atheism. Interpreting the word of Tawhid (definition), "La ilaha illa Allah" (there is no god but Allah), to mean "there is no existence but Allah" is invalid, as its correct meaning is "there is no god worthy of worship except Allah." As for the noble verse: (He is the First and the Last, the Manifest and the Hidden, and He is, of all things, Knowing) Al-Hadid/3, it does not indicate Wahdat al-Wujud, but rather the Oneness and perfection of Allah, and that the existence of the Creator is different from the existence of creation.