Allah is infinite and limitless…
Thus, it is impossible for Allah to have a center!
In order for something to have a center it must have defined parameters, so the intersection point of its corners can be called its center.
Whereas, Allah has no boundary!
If something has no boundaries it cannot have a center!
Hence, it follows that something without a center cannot have a core or shell, an interior or an exterior!
According to our five-sense perception and the material world we assume as a result of it, an object has inner and outer aspects: a core and a shell. But how can such concepts pertain to something that does not have a center?!
The Quran emphasizes this truth with the following verse:
“HU is the Awwal (the first and initial state of existence) and the Akhir (the infinitely subsequent One, to all manifestation), the Zahir (the explicit, unequivocal and perceivable manifestation; the Absolute Reality beyond the illusion) and the Batin (the unperceivable reality within the perceivable manifestation, the source of the unknown; the Absolute Self beyond the illusory selves)! He is Aleem over all things (the Knower of all things as their creator with His Names)!” (Quran 57:3)
That is, concepts such as the first, the subsequent, the outwardly explicit and the inwardly implicit all pertain to the same reality; all of it is Allah. The manifest and the hidden are not different things; it is our perception that defines them as different. The First, the Last, the Manifest and the Hidden all point to ALLAH.
Whether you refer to Allah as the Az-Zahir or the Al-Batin, whether you call Allah Al-Awwal or the Al-Akhir, all of these terms denote the same reality.
But if we had six or seven or even twelve senses rather than five, our concept of explicit and implicit would have been entirely different! Perhaps we would have perceived what is external or manifest to us today as internal or hidden, or vice versa!
The limitless, infinite ONE denoted by the name Allah is free from concepts such as explicit and implicit. These concepts are only so according to our assumptions.
Indeed, how can the One who is beyond conceptualized limitations, such as explicit-implicit and beginning-end, possibly end somewhere at which point a second form of existence begins? Clearly this is not possible! Therefore, every point to which thoughts or imagination can reach contains only the Essence of Allah, the Ahad, with all of His compositional qualities and attributes!
He who believes in the existence of another can only do so as a result of a lack of deep contemplation! This in religious terms is called shirq or duality.