Prophet Adam (peace be upon him) was ordered to not approach a specific tree in paradise (2:35); however, due to Satan's temptation, he approached it nevertheless (2:36). He felt remorseful for what he did and sought repentance, with Allah out of His Mercy, subsequently forgiving him (2:37). Despite that, Allah still had Prophet Adam (peace be upon him) leave paradise and be sent to earth (2:38).
A question that crosses some people's minds is why Allah would do this even after forgiving Prophet Adam (peace be upon him) for approaching the tree?
There are two ways of looking at this. One way could be to view Prophet Adam's (peace be upon him) expulsion from paradise as a punishment. How is that so? Bear in mind that Allah stated that Prophet Adam would be sent to earth (verse 36) before Prophet Adam (peace be upon him) repented (verse 37). Being forgiven could either be concerning a worldly punishment, afterlife punishment, or both. For example, the thief who gets his hand cut off still has to repent to Allah to avoid the punishment in the afterlife. Hence, Adam's (peace be upon him) descent to earth could have very well been a worldly punishment for his sin, yet he was forgiven so that he would not endure the punishment of hell in the afterlife.
A second way of looking at this matter is to not interpret Prophet Adam's (peace be upon him) expulsion from paradise as a punishment. Several Muslim scholars such as Imams Ar-Razi, Al-Qurtubi, Az-Zamakhshari, Al-Tha'alabi, Al-Nisapuri, and others have not understood this to imply a punishment. Rather, they saw that Prophet Adam's expulsion was out of mercy and teaching a lesson. They argued that it was that of mercy because with Prophet Adam's having gone to earth, he would learn to become a more responsible person and be encouraged to perform more acts of worship. That in and of itself is a great reward. It was also teaching him a lesson to see and contemplate how that one sin could drive him out of paradise, yet what would a large number of sins do? Hence, this would motivate him and us reading his story to realize and appreciate the seriousness of sin and how offensive it is to Allah.
From the beginning, Allah planned that Prophet Adam (peace be upon him) be stationed on earth. Allah said in Surah 2:30, "I am about to place a viceroy in the earth ."Notice that Allah did not say that He would place a viceroy in paradise but on earth.
Allah's placing of Prophet Adam (peace be upon him) in paradise initially is a helpful reminder to all of us to remember where our final destination should be and that our enemy Satan would do all he can to keep us away from it permanently.
One may argue that it is not fair that we are here on earth because of Prophet Adam's (peace be upon him) mistake. However, there are two things to bear in mind: 1) We were never meant to be in paradise before earth, only Prophet Adam (peace be upon him) and Eve were given that privilege, and 2) We would not have lasted in paradise either way, since we would have got kicked out after committing our first sin just like Prophet Adam (peace be upon him).
In conclusion, there is no difficulty in understanding how Allah ordered Prophet Adam (peace be upon him) to leave paradise because of his sin, yet still forgave him for that sin.
"Being forgiven could either be concerning a worldly punishment, afterlife punishment, or both. For example, the thief who gets his hand cut off still has to repent to Allah to avoid the punishment in the afterlife."
but there was no forgiveness for the theif when his hand was cut off .
if adam was sent to earth as punishment, then he was punished first, then forgiven later.
he cannot be punished and forgiven @ the same time, right?
they say there is no forgiveness in punishment. if i punish someone for a crime, have i forgiven them? so is the better interpretation which says that God destined adam to come to earth, not because of punishment.