God is the Creator of everything. He is the guardian over everything. Unto Him belong the keys of the heavens and the earth (39:62, 63).
No creature is there crawling on the earth, but its provision rests on God. He knows its lodging place and it repository (11:6).
If the Creator is Eternal and Everlasting, then His attributes must also be eternal and everlasting. He should not lose any of His attributes nor acquire new ones. If this is so, then His attributes are absolute. Can there be more than one Creator with such absolute attributes? Can there be for example, two absolutely powerful Creators? A moment's thought shows that this is not feasible.
The Quran summarizes this argument in the following verses:
God has not taken to Himself any son, nor is there any god with Him: For then each god would have taken of that which he created and some of them would have risen up over others (23:91).
And Why, were there gods in earth and heaven other than God, they (heaven and earth) would surely go to ruin (21:22).
The Oneness of God
The Quran reminds us of the falsity of all alleged gods. To the worshippers of man-made objects, it asks:
Do you worship what you have carved yourself? (37:95)
Or have you taken unto you others beside Him to be your protectors, even such as have no power either for good or for harm to themselves? (13:16)
To the worshippers of heavenly bodies it cites the story of Abraham:
When night outspread over him he saw a star and said, "This is my Lord." But when it set he said, "I love not the setters." When he saw the moon rising, he said, "This is my Lord." But when it set he said, "If my Lord does not guide me I shall surely be of the people gone astray." When he saw the sun rising, he said, "This is my Lord; this is greater." But when it set he said, "O my people, surely I quit that which you associate, I have turned my face to Him Who originated the heavens and the earth; a man of pure faith, I am not of the idolaters" (6:76-79).
The Believer's Attitude
In order to be a Muslim, i.e., to surrender oneself to God, it is necessary to believe in the oneness of God, in the sense of His being the only Creator, Preserver, Nourisher, etc. But this belief -- later on called "Tawhid Ar-Rububiyyah" -- is not enough. Many of the idolaters knew and believed that only the Supreme God could do all this, but that was not enough to make them Muslims. To tawhid ar-rububiyyah one must add tawhid al'uluhiyyah, i.e., one acknowledges the fact that is God alone Who deserves to be worshipped, and thus abstains from worshipping any other thing or being.
Having achieved this knowledge of the one true God, man should constantly have faith in Him, and should allow nothing to induce him to deny truth.
When faith enters a person's heart, it causes certain mental states that result in certain actions. Taken together these mental states and actions are the proof for the true faith. The Prophet said, "Faith is that which resides firmly in the heart and which is proved by deeds." Foremost among those mental states is the feeling of gratitude toward God, which could be said to be the essence of 'ibada' (worship).
The feeling of gratitude is so important that a non-believer is called 'kafir,' which means 'one who denies a truth' and also 'one who is ungrateful.'
A believer loves, and is grateful to God for the bounties He bestowed upon him, but being aware of the fact that his good deeds, whether mental or physical, are far from being commensurate with Divine favors, he is always anxious lest God should punish him, here or in the Hereafter. He, therefore, fears Him, surrenders himself to Him, and serves Him with great humility. One cannot be in such a mental state without being almost all the time mindful of God. Remembering God is thus the life force of faith, without which it fades and withers away.
The Quran tries to promote this feeling of gratitude by repeating the attributes of God very frequently. We find most of these attributes mentioned together in the following verses of the Quran:
He is God; there is no god but He, He is the Knower of the unseen and the visible; He is the All-Merciful, the All-Compassionate. He is God, there is no God but He. He is the King, the All-Holy, the All-Peace, the Guardian of Faith, the All-Preserver, the All-Mighty, the All-Compeller, the All-Sublime. Glory be to God, above that they associate! He is God the Creator, the Maker, the Shaper. To Him belong the Names Most Beautiful. All that is in the heavens and the earth magnifies Him; He is the All-Mighty, the All-Wise (59:22-24).