Quran effectiveness

Quran is the best and easiest way that reminds God for persons and is means of friendship with God. Therefore, Quran is the most important way that promotes persons to rank of righteous persons so that they can be under guardianship of God. If persons be under guardianship of God, God will organize all of their affairs and will be under guidance of God.
Satan tries to lead persons toward vices whereas prophets try to foster virtues of human. As Quran states
وَاعْلَمُوا أَنَّ فِيكُمْ رَسُولَ اللَّهِ ۚ لَوْ يُطِيعُكُمْ فِي كَثِيرٍ مِّنَ الْأَمْرِ لَعَنِتُّمْ وَلَٰكِنَّ اللَّهَ حَبَّبَ إِلَيْكُمُ الْإِيمَانَ وَزَيَّنَهُ فِي قُلُوبِكُمْ وَكَرَّهَ إِلَيْكُمُ الْكُفْرَ وَالْفُسُوقَ وَالْعِصْيَانَ ۚ أُولَٰئِكَ هُمُ الرَّاشِدُونَ
And know that among you is Allah´s Messenger: were he, in many matters, to follow your (wishes), ye would certainly fall into misfortune: But Allah has endeared the Faith to you, and has made it beautiful in your hearts, and He has made hateful to you Unbelief, wickedness, and rebellion: such indeed are those who walk in righteousness.
ا أَيُّهَا الَّذِينَ آمَنُوا لَا يَسْخَرْ قَوْمٌ مِّن قَوْمٍ عَسَىٰ أَن يَكُونُوا خَيْرًا مِّنْهُمْ وَلَا نِسَاءٌ مِّن نِّسَاءٍ عَسَىٰ أَن يَكُنَّ خَيْرًا مِّنْهُنَّ ۖ وَلَا تَلْمِزُوا أَنفُسَكُمْ وَلَا تَنَابَزُوا بِالْأَلْقَابِ ۖ بِئْسَ الِاسْمُ الْفُسُوقُ بَعْدَ الْإِيمَانِ ۚ وَمَن لَّمْ يَتُبْ فَأُولَٰئِكَ هُمُ الظَّالِمُونَ
O ye who believe! Let not some men among you laugh at others: It may be that the (latter) are better than the (former): Nor let some women laugh at others: It may be that the (latter are better than the (former): Nor defame nor be sarcastic to each other, nor call each other by (offensive) nicknames: Ill-seeming is a name connoting wickedness, (to be used of one) after he has believed: And those who do not desist are (indeed) doing wrong.
Amir Al-Momenin (peace be upon him) states
یا ایها الانسان الیس من نومک یقظة
Quran states about the religion of God
وَلَا تَحْسَبَنَّ الَّذِينَ قُتِلُوا فِي سَبِيلِ اللَّهِ أَمْوَاتًا ۚ بَلْ أَحْيَاءٌ عِندَ رَبِّهِمْ يُرْزَقُونَ
Think not of those who are slain in Allah´s way as dead. Nay, they live, finding their sustenance in the presence of their Lord.
وَمَن يُهَاجِرْ فِي سَبِيلِ اللَّهِ يَجِدْ فِي الْأَرْضِ مُرَاغَمًا كَثِيرًا وَسَعَةً ۚ وَمَن يَخْرُجْ مِن بَيْتِهِ مُهَاجِرًا إِلَى اللَّهِ وَرَسُولِهِ ثُمَّ يُدْرِكْهُ الْمَوْتُ فَقَدْ وَقَعَ أَجْرُهُ عَلَى اللَّهِ ۗ وَكَانَ اللَّهُ غَفُورًا رَّحِيمًا
He who forsakes his home in the cause of Allah, finds in the earth Many a refuge, wide and spacious: Should he die as a refugee from home for Allah and His Messenger, His reward becomes due and sure with Allah: And Allah is Oft-forgiving, Most Merciful.
وَإِذَا كُنتَ فِيهِمْ فَأَقَمْتَ لَهُمُ الصَّلَاةَ فَلْتَقُمْ طَائِفَةٌ مِّنْهُم مَّعَكَ وَلْيَأْخُذُوا أَسْلِحَتَهُمْ فَإِذَا سَجَدُوا فَلْيَكُونُوا مِن وَرَائِكُمْ وَلْتَأْتِ طَائِفَةٌ أُخْرَىٰ لَمْ يُصَلُّوا فَلْيُصَلُّوا مَعَكَ وَلْيَأْخُذُوا حِذْرَهُمْ وَأَسْلِحَتَهُمْ ۗ وَدَّ الَّذِينَ كَفَرُوا لَوْ تَغْفُلُونَ عَنْ أَسْلِحَتِكُمْ وَأَمْتِعَتِكُمْ فَيَمِيلُونَ عَلَيْكُم مَّيْلَةً وَاحِدَةً ۚ وَلَا جُنَاحَ عَلَيْكُمْ إِن كَانَ بِكُمْ أَذًى مِّن مَّطَرٍ أَوْ كُنتُم مَّرْضَىٰ أَن تَضَعُوا أَسْلِحَتَكُمْ ۖ وَخُذُوا حِذْرَكُمْ ۗ إِنَّ اللَّهَ أَعَدَّ لِلْكَافِرِينَ عَذَابًا مُّهِينًا
When thou (O Messenger) art with them, and standest to lead them in prayer, Let one party of them stand up (in prayer) with thee, Taking their arms with them: When they finish their prostrations, let them Take their position in the rear. And let the other party come up which hath not yet prayed - and let them pray with thee, Taking all precaution, and bearing arms: the Unbelievers wish, if ye were negligent of your arms and your baggage, to assault you in a single rush. But there is no blame on you if ye put away your arms because of the inconvenience of rain or because ye are ill; but take (every) precaution for yourselves. For the Unbelievers Allah hath prepared a humiliating punishment.
الَّذِينَ يَتَرَبَّصُونَ بِكُمْ فَإِن كَانَ لَكُمْ فَتْحٌ مِّنَ اللَّهِ قَالُوا أَلَمْ نَكُن مَّعَكُمْ وَإِن كَانَ لِلْكَافِرِينَ نَصِيبٌ قَالُوا أَلَمْ نَسْتَحْوِذْ عَلَيْكُمْ وَنَمْنَعْكُم مِّنَ الْمُؤْمِنِينَ ۚ فَاللَّهُ يَحْكُمُ بَيْنَكُمْ يَوْمَ الْقِيَامَةِ ۗ وَلَن يَجْعَلَ اللَّهُ لِلْكَافِرِينَ عَلَى الْمُؤْمِنِينَ سَبِيلًا
(These are) the ones who wait and watch about you: if ye do gain a victory from Allah, they say: "Were we not with you?"- but if the unbelievers gain a success, they say (to them): "Did we not gain an advantage over you, and did we not guard you from the believers?" but Allah will judge betwixt you on the Day of Judgment. And never will Allah grant to the unbelievers a way (to triumphs) over the believers.
يَسْتَفْتُونَكَ قُلِ اللَّهُ يُفْتِيكُمْ فِي الْكَلَالَةِ ۚ إِنِ امْرُؤٌ هَلَكَ لَيْسَ لَهُ وَلَدٌ وَلَهُ أُخْتٌ فَلَهَا نِصْفُ مَا تَرَكَ ۚ وَهُوَ يَرِثُهَا إِن لَّمْ يَكُن لَّهَا وَلَدٌ ۚ فَإِن كَانَتَا اثْنَتَيْنِ فَلَهُمَا الثُّلُثَانِ مِمَّا تَرَكَ ۚ وَإِن كَانُوا إِخْوَةً رِّجَالًا وَنِسَاءً فَلِلذَّكَرِ مِثْلُ حَظِّ الْأُنثَيَيْنِ ۗ يُبَيِّنُ اللَّهُ لَكُمْ أَن تَضِلُّوا ۗ وَاللَّهُ بِكُلِّ شَيْءٍ عَلِيمٌ
They ask thee for a legal decision. Say: Allah directs (thus) about those who leave no descendants or ascendants as heirs. If it is a man that dies, leaving a sister but no child, she shall have half the inheritance: If (such a deceased was) a woman, who left no child, Her brother takes her inheritance: If there are two sisters, they shall have two-thirds of the inheritance (between them): if there are brothers and sisters, (they share), the male having twice the share of the female. Thus doth Allah make clear to you (His law), lest ye err. And Allah hath knowledge of all things.
Persons are free to select path of vices or path of virtues as Quran states
وَهَدَيْنَاهُ النَّجْدَيْنِ
And shown him the two highways.
If persons follow virtues , they will be guided as Quran states
وَالَّذِينَ اهْتَدَوْا زَادَهُمْ هُدًى وَآتَاهُمْ تَقْوَاهُمْ
But to those who receive Guidance, He increases the (light of) Guidance, and bestows on them their Piety and Restraint (from evil).
مَّثَلُ الْجَنَّةِ الَّتِي وُعِدَ الْمُتَّقُونَ ۖ فِيهَا أَنْهَارٌ مِّن مَّاءٍ غَيْرِ آسِنٍ وَأَنْهَارٌ مِّن لَّبَنٍ لَّمْ يَتَغَيَّرْ طَعْمُهُ وَأَنْهَارٌ مِّنْ خَمْرٍ لَّذَّةٍ لِّلشَّارِبِينَ وَأَنْهَارٌ مِّنْ عَسَلٍ مُّصَفًّى ۖ وَلَهُمْ فِيهَا مِن كُلِّ الثَّمَرَاتِ وَمَغْفِرَةٌ مِّن رَّبِّهِمْ ۖ كَمَنْ هُوَ خَالِدٌ فِي النَّارِ وَسُقُوا مَاءً حَمِيمًا فَقَطَّعَ أَمْعَاءَهُمْ
(Here is) a Parable of the Garden which the righteous are promised: in it are rivers of water incorruptible; rivers of milk of which the taste never changes; rivers of wine, a joy to those who drink; and rivers of honey pure and clear. In it there are for them all kinds of fruits; and Grace from their Lord. (Can those in such Bliss) be compared to such as shall dwell forever in the Fire, and be given, to drink, boiling water, so that it cuts up their bowels (to pieces).
Quran states
قُلْ أَمَرَ رَبِّي بِالْقِسْطِ ۖ وَأَقِيمُوا وُجُوهَكُمْ عِندَ كُلِّ مَسْجِدٍ وَادْعُوهُ مُخْلِصِينَ لَهُ الدِّينَ ۚ كَمَا بَدَأَكُمْ تَعُودُونَ
Say: "My Lord hath commanded justice; and that ye set your whole selves (to Him) at every time and place of prayer, and call upon Him, making your devotion sincere as in His sight: such as He created you in the beginning, so shall ye return''.
وَنَزَعْنَا مَا فِي صُدُورِهِم مِّنْ غِلٍّ تَجْرِي مِن تَحْتِهِمُ الْأَنْهَارُ ۖ وَقَالُوا الْحَمْدُ لِلَّهِ الَّذِي هَدَانَا لِهَٰذَا وَمَا كُنَّا لِنَهْتَدِيَ لَوْلَا أَنْ هَدَانَا اللَّهُ ۖ لَقَدْ جَاءَتْ رُسُلُ رَبِّنَا بِالْحَقِّ ۖ وَنُودُوا أَن تِلْكُمُ الْجَنَّةُ أُورِثْتُمُوهَا بِمَا كُنتُمْ تَعْمَلُونَ
And We shall remove from their hearts any lurking sense of injury;- beneath them will be rivers flowing;- and they shall say: "Praise be to Allah, who hath guided us to this (felicity): never could we have found guidance, had it not been for the guidance of Allah: indeed it was the truth, that the messengers of our Lord brought unto us." And they shall hear the cry: "Behold! the garden before you! Ye have been made its inheritors, for your deeds (of righteousness).
هَلْ يَنظُرُونَ إِلَّا تَأْوِيلَهُ ۚ يَوْمَ يَأْتِي تَأْوِيلُهُ يَقُولُ الَّذِينَ نَسُوهُ مِن قَبْلُ قَدْ جَاءَتْ رُسُلُ رَبِّنَا بِالْحَقِّ فَهَل لَّنَا مِن شُفَعَاءَ فَيَشْفَعُوا لَنَا أَوْ نُرَدُّ فَنَعْمَلَ غَيْرَ الَّذِي كُنَّا نَعْمَلُ ۚ قَدْ خَسِرُوا أَنفُسَهُمْ وَضَلَّ عَنْهُم مَّا كَانُوا يَفْتَرُونَ
Do they just wait for the final fulfilment of the event? On the day the event is finally fulfilled, those who disregarded it before will say: "The messengers of our Lord did indeed bring true (tidings). Have we no intercessors now to intercede on our behalf? Or could we be sent back? then should we behave differently from our behaviour in the past." In fact they will have lost their souls, and the things they invented will leave them in the lurch.
سَأَصْرِفُ عَنْ آيَاتِيَ الَّذِينَ يَتَكَبَّرُونَ فِي الْأَرْضِ بِغَيْرِ الْحَقِّ وَإِن يَرَوْا كُلَّ آيَةٍ لَّا يُؤْمِنُوا بِهَا وَإِن يَرَوْا سَبِيلَ الرُّشْدِ لَا يَتَّخِذُوهُ سَبِيلًا وَإِن يَرَوْا سَبِيلَ الْغَيِّ يَتَّخِذُوهُ سَبِيلًا ۚ ذَٰلِكَ بِأَنَّهُمْ كَذَّبُوا بِآيَاتِنَا وَكَانُوا عَنْهَا غَافِلِينَ
Those who behave arrogantly on the earth in defiance of right - them will I turn away from My signs: Even if they see all the signs, they will not believe in them; and if they see the way of right conduct, they will not adopt it as the way; but if they see the way of error, that is the way they will adopt. For they have rejected our signs, and failed to take warning from them.
. وَإِذَا مَا أُنزِلَتْ سُورَةٌ نَّظَرَ بَعْضُهُمْ إِلَىٰ بَعْضٍ هَلْ يَرَاكُم مِّنْ أَحَدٍ ثُمَّ انصَرَفُوا ۚ صَرَفَ اللَّهُ قُلُوبَهُم بِأَنَّهُمْ قَوْمٌ لَّا يَفْقَهُونَ
Whenever there cometh down a Sura, they look at each other, (saying), "Doth anyone see you?" Then they turn aside: Allah hath turned their hearts (from the light); for they are a people that understand not.
فَخَلَفَ مِن بَعْدِهِمْ خَلْفٌ وَرِثُوا الْكِتَابَ يَأْخُذُونَ عَرَضَ هَٰذَا الْأَدْنَىٰ وَيَقُولُونَ سَيُغْفَرُ لَنَا وَإِن يَأْتِهِمْ عَرَضٌ مِّثْلُهُ يَأْخُذُوهُ ۚ أَلَمْ يُؤْخَذْ عَلَيْهِم مِّيثَاقُ الْكِتَابِ أَن لَّا يَقُولُوا عَلَى اللَّهِ إِلَّا الْحَقَّ وَدَرَسُوا مَا فِيهِ ۗ وَالدَّارُ الْآخِرَةُ خَيْرٌ لِّلَّذِينَ يَتَّقُونَ ۗ أَفَلَا تَعْقِلُونَ
After them succeeded an (evil) generation: They inherited the Book, but they chose (for themselves) the vanities of this world, saying (for excuse): "(Everything) will be forgiven us." (Even so), if similar vanities came their way, they would (again) seize them. Was not the covenant of the Book taken from them, that they would not ascribe to Allah anything but the truth? and they study.
what is in the Book. But best for the righteous is the home in the Hereafter. Will ye not understand?
يَحْلِفُونَ بِاللَّهِ مَا قَالُوا وَلَقَدْ قَالُوا كَلِمَةَ الْكُفْرِ وَكَفَرُوا بَعْدَ إِسْلَامِهِمْ وَهَمُّوا بِمَا لَمْ يَنَالُوا ۚ وَمَا نَقَمُوا إِلَّا أَنْ أَغْنَاهُمُ اللَّهُ وَرَسُولُهُ مِن فَضْلِهِ ۚ فَإِن يَتُوبُوا يَكُ خَيْرًا لَّهُمْ ۖ وَإِن يَتَوَلَّوْا يُعَذِّبْهُمُ اللَّهُ عَذَابًا أَلِيمًا فِي الدُّنْيَا وَالْآخِرَةِ ۚ وَمَا لَهُمْ فِي الْأَرْضِ مِن وَلِيٍّ وَلَا نَصِيرٍ
They swear by Allah that they said nothing (evil), but indeed they uttered blasphemy, and they did it after accepting Islam; and they meditated a plot which they were unable to carry out: this revenge of theirs was (their) only return for the bounty with which Allah and His Messenger had enriched them! If they repent, it will be best for them; but if they turn back (to their evil ways), Allah will punish them with a grievous penalty in this life and in the Hereafter: They shall have none on earth to protect or help them.
يَعْتَذِرُونَ إِلَيْكُمْ إِذَا رَجَعْتُمْ إِلَيْهِمْ ۚ قُل لَّا تَعْتَذِرُوا لَن نُّؤْمِنَ لَكُمْ قَدْ نَبَّأَنَا اللَّهُ مِنْ أَخْبَارِكُمْ ۚ وَسَيَرَى اللَّهُ عَمَلَكُمْ وَرَسُولُهُ ثُمَّ تُرَدُّونَ إِلَىٰ عَالِمِ الْغَيْبِ وَالشَّهَادَةِ فَيُنَبِّئُكُم بِمَا كُنتُمْ تَعْمَلُونَ
They will present their excuses to you when ye return to them. Say thou: "Present no excuses: we shall not believe you: Allah hath already informed us of the true state of matters concerning you: It is your actions that Allah and His Messenger will observe: in the end will ye be brought back to Him Who knoweth what is hidden and what is open: then will He show you the truth of all that ye did.