All praise and thanks belong to Allah the Most High, Great and Exalted. He is the Sustainer of the Universe, and the Provider for whatever exists in it; the Most Wise, the Supreme in Might, the Magnificent, and the Especially Merciful. He is the One to whom all affairs are referred. Glory be to Allah and may the His blessings and peace be upon the Prophet Muhammad, the Prophets before him (peace be upon them all), and all those who tread their path until the Day of Resurrection.
The Greatness of Allah is truly known only to Him the Almighty. The human brain and faculties, notwithstanding its outstanding supremacy over that of most of the other creatures of Allah, is still very limited, and cannot fully comprehend the conundrum of His greatness and mystery of His Personality. Notwithstanding, Allah the Great and Almighty God sent down scriptures to mankind wherein He gave a description of Himself the way man's brain capacity can cope with and comprehend Him. In the Qur'an Allah mentioned ninety-nine of His names and attributes all in a bid to draw His personality closer to human understanding.
To a lot of men, God is an Enigma; an inscrutable and mysterious personality. You do not have to apportion blame to anyone because, He called upon us to believe in (Him) in the unknown and unseen! What, in the Islamic belief is Iman bil-Ghaib, (The belief in the unknown); a cardinal part of the pillars of Islamic belief. Allah says,
"Whatever is in the heavens and earth exalts Allah, and He is the Exalted in Might, the Wise. His is the dominion of the heavens and earth. He gives life and causes death, and He is over all things competent. He is the First and the Last, the Ascendant and the Intimate, and He is, of all things, Knowing." (Q57:1-3).
You come to see that comprehending a Being Who happens to be the First and nothing was before Him, and is the Last and nothing shall be after Him; He is the Ascendant and at the same time the intimate, is quite cumbersome. That is why the righteous predecessors when asked concerning the qualities, attributes, names and very personality of Allah as described in the scriptures, they would reply that Allah possesses all that he attributed to Himself the way best befitting to Him (not the way we may necessarily picture it in our limited faculties), believing in them is obligatory and asking about the "how" is Bid'ah (innovation).
Allah greatness can be felt in His creation; the earth, heaven with the seven skies, the sun and the moon, the stars and the very air we breathe, on and on to the human being, the jinn and Angels, down to the animals and what can see as nature like the trees, rivers, seas, oceans, mountains, the volatility or fluctuation of the night and day and the various seasons of the year with their peculiarities, et-cetera, et-cetera! How Great and Magnificent indeed He is! Whenever one ponders and meditates over these things in the creation of God the Almighty one tends to get a glimpse of understanding of His personality.
Imam Abu Hanifah was said to have had a debate appointment with a polytheist; one who does not believe in the existence of God, one who does not believe that the creation has a Creator, and that everything just evolved on its own and all by its self! Just like Charles Darwin's theory of evolution. On the appointed day, the Imam was said to have delayed a lot and kept the audience waiting for long. When he finally appeared, he polytheist was fast to attack him for keeping people waiting and failing to keep to his appointment. The Imam tried giving the reason why he was late and told than that he lived at the other side of the river and needed a boat to cross over to the venue of the debate, but, unfortunately there were no boats to take him across. As he waited, he said, a tree fell down, cut itself into pieces and made itself into a boat, then he jumped onto it and it took him across the river to the other end. The polytheist shouted in mockery, where has anyone seen such happen? A tree fell itself and turned itself into a boat? Impossible! At this juncture, the Imam, to the amazement of all present said he was done with his debate. When asked how, he simply replied the polytheist that as long as he believes in the impossibility of such occurrence, likewise he ought to believe that man and all the things in creation can and would not have been able to evolve themselves!
Allah says in (Q3:190-191) "Indeed, in the creation of the heavens and the earth and the alternation of the night and the day are signs for those of understanding.Who remember Allah while standing or sitting or [lying] on their sides and give thought to (and ponder over) the creation of the heavens and the earth, [saying], "Our Lord, You did not create this aimlessly; exalted are You [above such a thing]; then protect us from the punishment of the Fire."
In a bid to bring His personality closer to mankind He said, "He is Allah, other than whom there is no deity, Knower of the unseen and the witnessed. He is the Most Gracious, the Most Merciful. He is Allah, other than whom there is no deity, the Sovereign, the Holy (Pure), the Perfection (free from all defects), the Bestower of Faith, the Overseer (Watcher over His creatures), the Exalted in Might, the Compeller, the Supreme. Glorified and Exalted is Allah above whatever they associate with Him. He is Allah, the Creator, the Inventor, the Fashioner; to Him belong the best names. Whatever is in the heavens and earth is exalting Him. And He is the Exalted in Might, the Wise. (Q59:22-24). And a lot other verses telling us and bringing to our awareness and understanding the greatness of Allah which can be seen clearly in the greatness of His creation.
"Then do they not look at the camels - how they are created? And at the sky - how it is raised? And at the mountains - how they are erected? And at the earth - how it is spread out? So remind, [O Muhammad]; you are only a reminder!" (Q88:17-21).
All these portray the greatness of the One Who invented and created the entire universe and all that can be found within it.