Unity of God

God is absolute existence and nothing is absent from God, whether they are material or immaterial things.
Quran states
أَلَمْ تَرَ أَنَّ اللَّهَ يَعْلَمُ مَا فِي السَّمَاوَاتِ وَمَا فِي الْأَرْضِ ۖ مَا يَكُونُ مِن نَّجْوَىٰ ثَلَاثَةٍ إِلَّا هُوَ رَابِعُهُمْ وَلَا خَمْسَةٍ إِلَّا هُوَ سَادِسُهُمْ وَلَا أَدْنَىٰ مِن ذَٰلِكَ وَلَا أَكْثَرَ إِلَّا هُوَ مَعَهُمْ أَيْنَ مَا كَانُوا ۖ ثُمَّ يُنَبِّئُهُم بِمَا عَمِلُوا يَوْمَ الْقِيَامَةِ ۚ إِنَّ اللَّهَ بِكُلِّ شَيْءٍ عَلِيمٌ
Seest thou not that Allah doth know (all) that is in the heavens and on earth? There is not a secret consultation between three, but He makes the fourth among them, - Nor between five but He makes the sixth,- nor between fewer nor more, but He is in their midst, wheresoever they be: In the end will He tell them the truth of their conduct, on the Day of Judgment. For Allah has full knowledge of all things.
لَّقَدْ كَفَرَ الَّذِينَ قَالُوا إِنَّ اللَّهَ ثَالِثُ ثَلَاثَةٍ ۘ وَمَا مِنْ إِلَٰهٍ إِلَّا إِلَٰهٌ وَاحِدٌ ۚ وَإِن لَّمْ يَنتَهُوا عَمَّا يَقُولُونَ لَيَمَسَّنَّ الَّذِينَ كَفَرُوا مِنْهُمْ عَذَابٌ أَلِيمٌ
They do blaspheme who say: Allah is one of three in a Trinity: for there is no god except One Allah. If they desist not from their word (of blasphemy), verily a grievous penalty will befall the blasphemers among them.
Quran mentions God as unity
لَّوْ أَرَادَ اللَّهُ أَن يَتَّخِذَ وَلَدًا لَّاصْطَفَىٰ مِمَّا يَخْلُقُ مَا يَشَاءُ ۚ سُبْحَانَهُ ۖ هُوَ اللَّهُ الْوَاحِدُ الْقَهَّارُ
Had Allah wished to take to Himself a son, He could have chosen whom He pleased out of those whom He doth create: but Glory be to Him! (He is above such things.) He is Allah, the One, the Irresistible.
يَوْمَ هُم بَارِزُونَ ۖ لَا يَخْفَىٰ عَلَى اللَّهِ مِنْهُمْ شَيْءٌ ۚ لِّمَنِ الْمُلْكُ الْيَوْمَ ۖ لِلَّهِ الْوَاحِدِ الْقَهَّارِ
The Day whereon they will (all) come forth: not a single thing concerning them is hidden from Allah. Whose will be the dominion that Day?" That of Allah, the One the Irresistible.
Before Loqman mentions advisory words about advising his child, Quran states
وَلَقَدْ آتَيْنَا لُقْمَانَ الْحِكْمَةَ أَنِ اشْكُرْ لِلَّهِ ۚ وَمَن يَشْكُرْ فَإِنَّمَا يَشْكُرُ لِنَفْسِهِ ۖ وَمَن كَفَرَ فَإِنَّ اللَّهَ غَنِيٌّ حَمِيدٌ we bestowed (in the past) Wisdom on Luqman: "Show (thy) gratitude to Allah. Any who is (so) grateful does so to the profit of his own soul: but if any is ungrateful, verily Allah is free of all wants, Worthy of all praise.
يُؤْتِي الْحِكْمَةَ مَن يَشَاءُ ۚ وَمَن يُؤْتَ الْحِكْمَةَ فَقَدْ أُوتِيَ خَيْرًا كَثِيرًا ۗ وَمَا يَذَّكَّرُ إِلَّا أُولُو الْأَلْبَابِ
He granteth wisdom to whom He pleaseth; and he to whom wisdom is granted receiveth indeed a benefit overflowing; but none will grasp the Message but men of understanding.
يَا بُنَيَّ إِنَّهَا إِن تَكُ مِثْقَالَ حَبَّةٍ مِّنْ خَرْدَلٍ فَتَكُن فِي صَخْرَةٍ أَوْ فِي السَّمَاوَاتِ أَوْ فِي الْأَرْضِ يَأْتِ بِهَا اللَّهُ ۚ إِنَّ اللَّهَ لَطِيفٌ خَبِيرٌ
O my son!" (said Luqman), "If there be (but) the weight of a mustard-seed and it were (hidden) in a rock, or (anywhere) in the heavens or on earth, Allah will bring it forth: for Allah understands the finest mysteries, (and) is well-acquainted (with them).
When idol worshippers were invited to monotheism, they said
أَجَعَلَ الْآلِهَةَ إِلَٰهًا وَاحِدًا ۖ إِنَّ هَٰذَا لَشَيْءٌ عُجَابٌ
Has he made the gods (all) into one Allah? Truly this is a wonderful thing.
The prophet (peace of Allah be upon him and his descendants) denies different Gods and invites us to a unique God;
سَبَّحَ لِلَّهِ مَا فِي السَّمَاوَاتِ وَالْأَرْضِ ۖ وَهُوَ الْعَزِيزُ الْحَكِيمُ
Whatever is in the heavens and on earth,- let it declare the Praises and Glory of Allah: for He is the Exalted in Might, the Wise.
Quran states about God
سُبْحَانَ الَّذِي أَسْرَىٰ بِعَبْدِهِ لَيْلًا مِّنَ الْمَسْجِدِ الْحَرَامِ إِلَى الْمَسْجِدِ الْأَقْصَى الَّذِي بَارَكْنَا حَوْلَهُ لِنُرِيَهُ مِنْ آيَاتِنَا ۚ إِنَّهُ هُوَ السَّمِيعُ الْبَصِيرُ
Glory to (Allah) Who did take His servant for a Journey by night from the Sacred Mosque to the farthest Mosque, whose precincts We did bless,- in order that We might show him some of Our Signs: for He is the One Who heareth and seeth (all things).
Quran proves awareness and understanding for all creatures all over the world;
لَهُ مُلْكُ السَّمَاوَاتِ وَالْأَرْضِ ۖ يُحْيِي وَيُمِيتُ ۖ وَهُوَ عَلَىٰ كُلِّ شَيْءٍ قَدِيرٌ
To Him belongs the dominion of the heavens and the earth: It is He Who gives Life and Death; and He has Power over all things.
Quran states about absolute power of God
وَ الْأَوَّلُ وَالْآخِرُ وَالظَّاهِرُ وَالْبَاطِنُ ۖ وَهُوَ بِكُلِّ شَيْءٍ عَلِيمٌ
He is the First and the Last, the Evident and the Immanent: and He has full knowledge of all things.
God states about different sciences
هُوَ الَّذِي خَلَقَ السَّمَاوَاتِ وَالْأَرْضَ فِي سِتَّةِ أَيَّامٍ ثُمَّ اسْتَوَىٰ عَلَى الْعَرْشِ ۚ يَعْلَمُ مَا يَلِجُ فِي الْأَرْضِ وَمَا يَخْرُجُ مِنْهَا وَمَا يَنزِلُ مِنَ السَّمَاءِ وَمَا يَعْرُجُ فِيهَا ۖ وَهُوَ مَعَكُمْ أَيْنَ مَا كُنتُمْ ۚ وَاللَّهُ بِمَا تَعْمَلُونَ بَصِيرٌ
He it is Who created the heavens and the earth in Six Days, and is moreover firmly established on the Throne (of Authority). He knows what enters within the earth and what comes forth out of it, what comes down from heaven and what mounts up to it. And He is with you wheresoever ye may be. And Allah sees well all that ye do.
God is aware of whatever is descended on the earth;
هُوَ الَّذِي خَلَقَ السَّمَاوَاتِ وَالْأَرْضَ فِي سِتَّةِ أَيَّامٍ ثُمَّ اسْتَوَىٰ عَلَى الْعَرْشِ ۚ يَعْلَمُ مَا يَلِجُ فِي الْأَرْضِ وَمَا يَخْرُجُ مِنْهَا وَمَا يَنزِلُ مِنَ السَّمَاءِ وَمَا يَعْرُجُ فِيهَا ۖ وَهُوَ مَعَكُمْ أَيْنَ مَا كُنتُمْ ۚ وَاللَّهُ بِمَا تَعْمَلُونَ بَصِيرٌ
He it is Who created the heavens and the earth in Six Days, and is moreover firmly established on the Throne (of Authority). He knows what enters within the earth and what comes forth out of it, what comes down from heaven and what mounts up to it. And He is with you wheresoever ye may be. And Allah sees well all that ye do .
Quran states about believers
إِنَّ اللَّهَ مَعَ الَّذِينَ اتَّقَوا وَّالَّذِينَ هُم مُّحْسِنُونَ
For Allah is with those who restrain themselves, and those who do good.
Quran recommends mentioning name of God and remembering him;
يَا أَيُّهَا الَّذِينَ آمَنُوا اذْكُرُوا اللَّهَ ذِكْرًا كَثِيرًا
. O ye who believe! Celebrate the praises of Allah, and do this often
Imam Sadeq (peace be upon him) states
''و اخلاصه أن تحجزه لَا إِلَهَ إِلَّا اللَّهُ عما حرم الله علیه''
Quran states
یا أَيُّهَا الَّذِينَ آمَنُوا لَا تُحِلُّوا شَعَائِرَ اللَّهِ وَلَا الشَّهْرَ الْحَرَامَ وَلَا الْهَدْيَ وَلَا الْقَلَائِدَ وَلَا آمِّينَ الْبَيْتَ الْحَرَامَ يَبْتَغُونَ فَضْلًا مِّن رَّبِّهِمْ وَرِضْوَانًا ۚ وَإِذَا حَلَلْتُمْ فَاصْطَادُوا ۚ وَلَا يَجْرِمَنَّكُمْ شَنَآنُ قَوْمٍ أَن صَدُّوكُمْ عَنِ الْمَسْجِدِ الْحَرَامِ أَن تَعْتَدُوا ۘ وَتَعَاوَنُوا عَلَى الْبِرِّ وَالتَّقْوَىٰ ۖ وَلَا تَعَاوَنُوا عَلَى الْإِثْمِ وَالْعُدْوَانِ ۚ وَاتَّقُوا اللَّهَ ۖ إِنَّ اللَّهَ شَدِيدُ الْعِقَابِ
O ye who believe! Violate not the sanctity of the symbols of Allah, nor of the sacred month, nor of the animals brought for sacrifice, nor the garlands that mark out such animals, nor the people resorting to the sacred house, seeking of the bounty and good pleasure of their Lord. But when ye are clear of the sacred precincts and of pilgrim garb, ye may hunt and let not the hatred of some people in (once) shutting you out of the Sacred Mosque lead you to transgression (and hostility on your part). Help ye one another in righteousness and piety, but help ye not one another in sin and rancour: fear Allah: for Allah is strict in punishment.
حُرِّمَتْ عَلَيْكُمُ الْمَيْتَةُ وَالدَّمُ وَلَحْمُ الْخِنزِيرِ وَمَا أُهِلَّ لِغَيْرِ اللَّهِ بِهِ وَالْمُنْخَنِقَةُ وَالْمَوْقُوذَةُ وَالْمُتَرَدِّيَةُ وَالنَّطِيحَةُ وَمَا أَكَلَ السَّبُعُ إِلَّا مَا ذَكَّيْتُمْ وَمَا ذُبِحَ عَلَى النُّصُبِ وَأَن تَسْتَقْسِمُوا بِالْأَزْلَامِ ۚ ذَٰلِكُمْ فِسْقٌ ۗ الْيَوْمَ يَئِسَ الَّذِينَ كَفَرُوا مِن دِينِكُمْ فَلَا تَخْشَوْهُمْ وَاخْشَوْنِ ۚ الْيَوْمَ أَكْمَلْتُ لَكُمْ دِينَكُمْ وَأَتْمَمْتُ عَلَيْكُمْ نِعْمَتِي وَرَضِيتُ لَكُمُ الْإِسْلَامَ دِينًا ۚ فَمَنِ اضْطُرَّ فِي مَخْمَصَةٍ غَيْرَ مُتَجَانِفٍ لِّإِثْمٍ ۙ فَإِنَّ اللَّهَ غَفُورٌ رَّحِيمٌ
Forbidden to you (for food) are: dead meat, blood, the flesh of swine, and that on which hath been invoked the name of other than Allah; that which hath been killed by strangling, or by a violent blow, or by a headlong fall, or by being gored to death; that which hath been (partly) eaten by a wild animal; unless ye are able to slaughter it (in due form); that which is sacrificed on stone (altars); (forbidden) also is the division (of meat) by raffling with arrows: that is impiety. This day have those who reject faith given up all hope of your religion: yet fear them not but fear Me. This day have I perfected your religion for you, completed My favour upon you, and have chosen for you Islam as your religion. But if any is forced by hunger, with no inclination to transgression, Allah is indeed Oft-forgiving, Most Merciful.
الْيَوْمَ أُحِلَّ لَكُمُ الطَّيِّبَاتُ ۖ وَطَعَامُ الَّذِينَ أُوتُوا الْكِتَابَ حِلٌّ لَّكُمْ وَطَعَامُكُمْ حِلٌّ لَّهُمْ ۖ وَالْمُحْصَنَاتُ مِنَ الْمُؤْمِنَاتِ وَالْمُحْصَنَاتُ مِنَ الَّذِينَ أُوتُوا الْكِتَابَ مِن قَبْلِكُمْ إِذَا آتَيْتُمُوهُنَّ أُجُورَهُنَّ مُحْصِنِينَ غَيْرَ مُسَافِحِينَ وَلَا مُتَّخِذِي أَخْدَانٍ ۗ وَمَن يَكْفُرْ بِالْإِيمَانِ فَقَدْ حَبِطَ عَمَلُهُ وَهُوَ فِي الْآخِرَةِ مِنَ الْخَاسِرِينَ
This day are (all) things good and pure made lawful unto you. The food of the People of the Book is lawful unto you and yours is lawful unto them. (Lawful unto you in marriage) are (not only) chaste women who are believers, but chaste women among the People of the Book, revealed before your time,- when ye give them their due dowers, and desire chastity, not lewdness, nor secret intrigues if any one rejects faith, fruitless is his work, and in the Hereafter he will be in the ranks of those who have lost (all spiritual good).
يَا أَيُّهَا الَّذِينَ آمَنُوا إِذَا قُمْتُمْ إِلَى الصَّلَاةِ فَاغْسِلُوا وُجُوهَكُمْ وَأَيْدِيَكُمْ إِلَى الْمَرَافِقِ وَامْسَحُوا بِرُءُوسِكُمْ وَأَرْجُلَكُمْ إِلَى الْكَعْبَيْنِ ۚ وَإِن كُنتُمْ جُنُبًا فَاطَّهَّرُوا ۚ وَإِن كُنتُم مَّرْضَىٰ أَوْ عَلَىٰ سَفَرٍ أَوْ جَاءَ أَحَدٌ مِّنكُم مِّنَ الْغَائِطِ أَوْ لَامَسْتُمُ النِّسَاءَ فَلَمْ تَجِدُوا مَاءً فَتَيَمَّمُوا صَعِيدًا طَيِّبًا فَامْسَحُوا بِوُجُوهِكُمْ وَأَيْدِيكُم مِّنْهُ ۚ مَا يُرِيدُ اللَّهُ لِيَجْعَلَ عَلَيْكُم مِّنْ حَرَجٍ وَلَٰكِن يُرِيدُ لِيُطَهِّرَكُمْ وَلِيُتِمَّ نِعْمَتَهُ عَلَيْكُمْ لَعَلَّكُمْ تَشْكُرُونَ
O ye who believe! when ye prepare for prayer, wash your faces, and your hands (and arms) to the elbows; Rub your heads (with water); and (wash) your feet to the ankles. If ye are in a state of ceremonial impurity, bathe your whole body. But if ye are ill, or on a journey, or one of you cometh from offices of nature, or ye have been in contact with women, and ye find no water, then take for yourselves clean sand or earth, and rub therewith your faces and hands, Allah doth not wish to place you in a difficulty, but to make you clean, and to complete his favour to you, that ye may be grateful.
وْمَ يَقُولُ الْمُنَافِقُونَ وَالْمُنَافِقَاتُ لِلَّذِينَ آمَنُوا انظُرُونَا نَقْتَبِسْ مِن نُّورِكُمْ قِيلَ ارْجِعُوا وَرَاءَكُمْ فَالْتَمِسُوا نُورًا فَضُرِبَ بَيْنَهُم بِسُورٍ لَّهُ بَابٌ بَاطِنُهُ فِيهِ الرَّحْمَةُ وَظَاهِرُهُ مِن قِبَلِهِ الْعَذَابُ
One Day will the Hypocrites- men and women - say to the Believers: "Wait for us! Let us borrow (a Light) from your Light!" It will be said: "Turn ye back to your rear! then seek a Light (where ye can)!" So a wall will be put up betwixt them, with a gate therein. Within it will be Mercy throughout, and without it, all alongside, will be (Wrath and) Punishment.
أَلَمْ يَأْنِ لِلَّذِينَ آمَنُوا أَن تَخْشَعَ قُلُوبُهُمْ لِذِكْرِ اللَّهِ وَمَا نَزَلَ مِنَ الْحَقِّ وَلَا يَكُونُوا كَالَّذِينَ أُوتُوا الْكِتَابَ مِن قَبْلُ فَطَالَ عَلَيْهِمُ الْأَمَدُ فَقَسَتْ قُلُوبُهُمْ ۖ وَكَثِيرٌ مِّنْهُمْ فَاسِقُونَ
Has not the Time arrived for the Believers that their hearts in all humility should engage in the remembrance of Allah and of the Truth which has been revealed (to them), and that they should not become like those to whom was given Revelation aforetime, but long ages passed over them and their hearts grew hard? For many among them are rebellious transgressors.