Allah (Subhanahu Wa Ta'ala) is best introduced in the following short chapter of the Qur'an.
In the name of Allah, the beneficent, the merciful. Say: he is Allah, the One and Only! Allah, the Eternally Besought of all, He Begets not, nor was He begotten and there is none equal to Him. ( 112:1-4 )
Confirming the absolute unity of Allah (Subhanahu Wa Ta'ala) the Qur'an says:
Allah! There is no God save him, the Alive, the Eternal; neither slumber nor sleep overtakes him. Unto Him belongs and what is in the earth. Who is he that intercedes with Him except by His leave? He knows that which is before them and that which is behind them; while they encompass nothing of His knowledge save according to his will. His chair contains the heavens and the earth; and He is never weary of preserving them. And He is the Sublime, the Tremendous. ( 2:255 )
The above is the greatest verse in the holy Qur'an. It mentions Allah (Subhanahu Wa Ta'ala) not less than sixteen times, both in name and through different pronouns referring to him.
The opening chapter of the Qur'an gives more light Concerning Allah (Subhanahu Wa Ta'ala). This chapter is called the mother of the book. Although it is a short chapter as it is composed of seven short Verses, it is however, the most precious gem in the Qur'an. Here is a translation of it:
In one sacred Hadith whose words are the prophet's but whose meaning is a divine inspiration Allah (Subhanahu Wa Ta'ala) says: " I have divided prayer between Me and My slave, and unto my slave will be granted what he asks for ".(2)
One more verse confirming the oneness of Allah (Subhanahu Wa Ta'ala) is:
And your god is one god; there is no god except he, the beneficent, the merciful.( 2:163 )
The Qur'an's approach to prove the oneness of Allah (Subhanahu Wa Ta'ala) is through drawing our attention to his creation: one example is the following:
in the creation of the heavens and the earth, and the difference of night and day, and the ships that run upon the sea with what is useful to mankind, and the water which Allah sends down from the sky, thereby reviving the earth after its death, and spreading all kinds of beasts therein and the Dispensation of winds and the subservient clouds between Heaven and earth are miracles for those who have sense. ( 2:164 )
Another similar verse occurs in chapter 3:190 where Allah (Subhanahu Wa Ta'ala) says:
in the creation of the heavens and the earth and the Difference of night and day are miracles for those who have sense; those who remember Allah standing, sitting and Reclining on their sides. They contemplate the creation of Heavens and earth (and say): our lord! You have not created this in vain! Glory be to you. So protect us from the doom of fire.
This verse states clearly the purpose of creation and mentions the fate of people who deviate:
Our lord! He whom you cause to enter the fire, him indeed you have scandalized. And for wrong doers there will be no helpers. Our lord! We have heard a caller unto faith: believe in your lord! So we believed. Therefore our lord! Forgive us our sins and remit from us our evil deeds and make us die along with the righteous. Our lord! And grant us that which you have promised us through your apostles and confound us not on the day of judgement. You never break the promise.( 3:190-194 )
The Qur'an says that these people's prayer was not lost in a wilderness. It was accepted by Allah (Subhanahu Wa Ta'ala):
so their lord responded to them: I suffer not the work of any worker among you, male or female, to be lost; for you proceed one from another. Thus those who emigrated and were expelled from their homes, and were hurt for my cause, and fought and were slain, I shall remit their evil deeds from them and I shall welcome them into gardens underneath which rivers flow, a reward from Allah - and with Allah is the fairest of rewards.( 3:195 )
Source: Muslim World League - Canadian Office