Allah tells us that He did not create the creatures in vain; He created them to worship Him Alone, then He will gather them on the Day of Gathering and will reward the obedient and punish the disbelievers. Allah says:

﴿وَمَا خَلَقْنَا السَّمَآءَ وَالاٌّرْضَ وَمَا بَيْنَهُمَا بَـطِلاً ذَلِكَ ظَنُّ الَّذِينَ كَفَرُواْ﴾

(And We created not the heaven and the earth and all that is between them without purpose! That is the consideration of those who disbelieve!) meaning, those who do not think that the resurrection and the place of return will occur, but they think that there is nothing after this world.

﴿فَوَيْلٌ لِّلَّذِينَ كَفَرُواْ مِنَ النَّارِ﴾

(Then woe to those who disbelieve from the Fire!) means, woe to them on the Day when they will be resurrected, from the Fire that is prepared for them. Then Allah explains that because of His justice and wisdom, He does not treat the believers and the disbelievers equally. Allah says:

﴿أَمْ نَجْعَلُ الَّذِينَ ءَامَنُواْ وَعَمِلُواْ الصَّـلِحَـتِ كَالْمُفْسِدِينَ فِى الاٌّرْضِ أَمْ نَجْعَلُ الْمُتَّقِينَ كَالْفُجَّارِ ﴾

(Shall We treat those who believe and do righteous good deeds as those who do mischief on the earth Or shall We treat Those who have Taqwa as the evildoers) meaning, `We shall not do that.' They are not equal before Allah, and since this is the case, there must inevitably be another realm in which those who obey Allah will be rewarded and the wicked will be punished. This teaching indicates to those of a sound mind and upright nature that there must inevitably be a resurrection and recompense. We see evildoers and criminals are prospering and increasing in wealth, children and luxury, until they die in that state. We see oppressed believers dying of grief and distress, so by the wisdom of the All-Wise, All-Knowing, All-Just who does not do even a speck of dust's weight of injustice, there should be a time when the rights of the oppressed are restored with due justice. If this does not happen in this world, there must be another realm where recompense may be made and consolation may be found. The Qur'an teaches sound aims based on a rational way of thinking, so Allah says:

﴿كِتَـبٌ أَنزَلْنَـهُ إِلَيْكَ مُبَـرَكٌ لِّيَدَّبَّرُواْ ءَايَـتِهِ وَلِيَتَذَكَّرَ أُوْلُو الاٌّلْبَـبِ ﴾

((This is) a Book which We have sent down to you, full of blessings, that they may ponder over its Ayat, and that men of understanding may remember.) meaning, those who are possessed of wisdom and reason.

﴿وَوَهَبْنَا لِدَاوُودَ سُلَيْمَـنَ نِعْمَ الْعَبْدُ إِنَّهُ أَوَّابٌ - إِذْ عُرِضَ عَلَيْهِ بِالْعَشِىِّ الصَّـفِنَـتُ الْجِيَادُ - فَقَالَ إِنِّى أَحْبَبْتُ حُبَّ الْخَيْرِ عَن ذِكْرِ رَبِى حَتَّى تَوَارَتْ بِالْحِجَابِ - رُدُّوهَا عَلَىَّ فَطَفِقَ مَسْحاً بِالسُّوقِ وَالاٌّعْنَاقِ ﴾

(30. And to Dawud We gave Sulayman. How excellent a servant! Verily, he was ever turning in repentance (to Us)!) (31. When there were displayed before him, in the afternoon, well trained horses of the highest breed.) (32. He said: "I did love the good instead of remembering my Lord,'' till the time was over, and (the sun) had hidden in the veil (of night).) (33. Then he said: "Bring them back to me.'' Then he began to pass his hand over their legs and their necks.)