In the Name of Allah, the All-Compassionate, the All-Merciful.
In Ayah 38 of Surah al-Baqara, God Almighty recounting to us the deceit of the devil towards Adam and Eve, says:
قُلْنَا اهْبِطُوا مِنْهَا جَمِيعًا ۖ فَإِمَّا يَأْتِيَنَّكُم مِّنِّي هُدًى فَمَن تَبِعَ هُدَايَ فَلَا خَوْفٌ عَلَيْهِمْ وَلَا هُمْ يَحْزَنُونَ
We said: 'Get down from it, all together! Yet, should any guidance come to you from Me, those who follow My guidance shall have no fear, nor shall they grieve. (2:38)
After accepting Adam's repentance, the All-compassionate God ordered the first human pair to leave the garden so that they should not think that penitence after sin might cause them to stay in paradise-like gardens. True, Allah's forgiveness removes the stain of sins absolves the sinners of punishment but traces of the sins committed remain, so as to be reminder against future violation of divine commandments.
Adam's exit from the paradise was the natural result of eating of the forbidden tree. Repentance does not mean he and his wife would be allowed to stay. Adam and Eve had to leave paradise and look for residence in other parts of the earth with less facilities and bounties.
Since Adam's exit from paradise meant his progeny to come should not consider paradise as something taken for granted, but will have to strive through discernment between virtue and vice, to deserve it. Thus the command to Adam and Eve to get out of the paradise-like garden was issued publicly and here all human beings are being addressed. But, God mentions guidance immediately after this expulsion. God means to say: I have provided all means of guidance, whether Books or the Messengers, but, unfortunately all children of Adam, fail to avail of this divine bounty.
Some heed the commandments of the Lord Most High and are thus guided towards virtue and bliss in afterlife, while some others refuse to obey the Creator, turn away from guidance through their evil deeds, and are thus doomed as infidels and unrepentant sinners.
Allah taught the names of the creatures and the realities of creation to Adam, for; He had already given Adam the capacity and capability to absorb such issues. This very knowledge is the reason of Adam's superiority over the angels. Yet this power couldn't vouchsafe him against Satan's temptations and he was deceived very easily.
Thus God, having accepted Adam's repentance and arranged for his dwelling on the earth, prepared the means of his guidance as well, so that he and his progeny could distinguish good from evil and the right from the wrong. Sending revelation was the second divine bounty bestowed to Adam, besides wisdom.
Although sending revelation and the means of guidance is necessary, being guided is in man's disposal and it is not something forced upon him, so as to test him. So human beings are free to choose their way either to accept the divine guidance and earn eternal rewards, or to disobey it and doom themselves forever.
Man is most of all concerned about his future in the world and the Hereafter. In view of this he takes stock of his past life and grieves at the lost opportunities and chances. But if a person accepts divine guidance Allah will guarantee his or her future and there will be no concern or anxiety for him or her, and he or she will not feel aggrieved of the past, because he or she has acted according to the duty although seemingly there were no worldly achievements. The points we learn from this Ayah are as follows:
1. Sometimes a wrong action will make a generation or race to suffer. Adam (Peace upon him) didn't do but a single wrong action yet he was expelled from paradise-like gardens.
2. God will never deprive man from his grace. Thus though Adam disobeyed Allah, God not only opened the door of repentance for him but also prepared the means for his guidance.
3. Divine guidance started with man's residence on the earth and the real guidance only comes from Allah.
4. Freedom of choice is a human characteristic. In view of this people are not forced to accept guidance, therefore a group of them are guided while another group tries to deny the truth and becomes infidels.
5. Those who avail of divine guidance achieve real tranquility and are distant from any anxiety and concern.
In Ayah 39 of surah Baqara we read:
وَالَّذِينَ كَفَرُوا وَكَذَّبُوا بِآيَاتِنَا أُولَـٰئِكَ أَصْحَابُ النَّارِ ۖ هُمْ فِيهَا خَالِدُونَ
"But those who are faithless and deny our signs, they shall be the inmates of the Fire and they shall remain in it [for ever]." (2:39)
Besides those who accept divine guidance freely there are people who ignore Allah's signs and deny them. The first group achieves eternal bliss while the second ends up in hell.
God's means of guidance are His manifest signs. But if a person denies them out of infidelity and turns away from the right, not only he or she doesn't accept these signs but also says these are not from God.
Eventually such people will end up in the Fire on Doomsday. And since denial of the truth and the right had been their characteristic they will stay in Fire forever.
From this Ayah we learn that Allah has provided the means of guidance for infidels, too, but they themselves have not accepted them intentionally and therefore they have bought the fire of the Hell.