Your Saying “God is Most Great” does not mean that He is greater than something else, since there is nothing else alongside of Him, so that it could be said that He is greater than it. Rather, the meaning of Allahu Akbar is that He is much too great to be perceived by the senses or for the depths of His Majesty to be reached by reason and logic, and indeed, that He is much too great to be known by an other-than-Him for truly, no one knows God but God.