Creating another God is impossible because such a God will be created whereas Allah taala always existed. Secondly, this "God" will have a beginning whereas Allah taala has no beginning. Thus for these reasons there can never be the like of Allah taala. A person may say but that means Allah taala is not all-powerful. The reply to this is that we do not believe that to be considered all-powerful requires the doing of the impossible. Just as when a father says to his son at a shop "You can have anything." No one will say that this statement is incorrect because the son cannot have the cash register or the shopkeeper. The reason for this is because these things are excluded most obviously. Similarly, Allah taala's being all powerful means He can do that which no other can do. But excluded from this are such things which would negate His being God and things that are beyond possibility. He is nevertheless "All-powerful" for there is none that can compare to Him in His power and knowledge. He sees and hears everything and he creates absolutely everything. He created every living thing of the trillions of things that exist in this universe, and there is nothing of His creation that can change what He wills to happen, His will is supreme. His power is such that all that is needed for Him to create a billion more such great universes is to merely will it and they will come into existence.

This example is what our limited minds can conclude about Him, due to our limitedness in knowledge and experience, thus this human incapacity should make us awe-struck of Him, because if that is his power, that our feeble limited minds can grasp, what must be the reality of His power? Thus there can be no doubt He is the All-Powerful.