An interesting excerpt from ReligionFacts.com
[Some] Muslim commentators, noting that Allah can rescue people from hell as he chooses, and that he is merciful and compassionate, have hypothesized that eventually hell will be empty. Alternatively, Hell can be seen as a place of progress where souls are instructed until they are fit to go to heaven:
“Life after death is actually the starting-point of further progress for man. Those in paradise are advancing to higher and higher stages in knowledge and perfection of faith. Hell is meant to purify those in it of the effects of their bad deeds, and so make them fit for further advancement. Its punishment is, therefore, not everlasting.” (Source: Muslim.org, an Ahmadiyya website)
Here’s a great article from the New York Times about the basics of Muslim conceptions of the afterlife. This part feels like it wants attention:
But what happens to the vast majority of Muslims, those who do not die as martyrs?
According to Islamic doctrine, between the moment of death and the burial ceremony, the spirit of a deceased Muslim takes a quick journey to Heaven and Hell, where it beholds visions of the bliss and torture awaiting humanity at the end of days.
By the time corpse handlers are ready to wash the body, the spirit returns to earth to observe the preparations for burial and to accompany the procession toward the cemetery. But then, before earth is piled upon the freshly dug grave, an unusual reunion takes place: The spirit returns to dwell within the body.
In the grave, the deceased Muslim – this composite of spirit and corpse – encounters two terrifying angels, Munkar and Nakir, recognized by their bluish faces, their huge teeth and their wild hair.
These angels carry out a trial to probe the soundness of a Muslim’s faith. If the dead Muslim answers their questions convincingly and if he has no sin on record, then the grave is transformed into a luxurious space that makes bearable the long wait until the final judgment.
But if a Muslim’s faith is imperfect or if he has sinned during life by, for example, failing repeatedly to undertake purity rituals before prayer, then the grave is transformed into an oppressive, constricting space.
The earth begins to weigh down heavily upon the sentient corpse, until the rib cage collapses; worms begin to nibble away at the flesh, causing horrible pain.
This torture does not continue indefinitely. It occurs intermittently and ends at the very latest with the resurrection – when God may well forgive Muslims who have endured the punishment.
Muslims can escape the torture of the grave by dying as martyrs. In Islam the category of martyr does not belong exclusively to those who die fighting in God’s path. According to Islamic tradition, Muslims who die in a fire, by drowning, in the collapse of a building or in some other way involving great physical suffering merit the rank of martyrs in the afterlife.
This means that immediately after death, their spirits do not return to dwell within mutilated or burned corpses. Instead they enter the Garden of Eden, where they receive new bodies, perfectly reformed, so as to enjoy the rewards of martyrdom until the resurrection. Those who have lost a relative in a violent and shocking death – in the bombings in Baghdad, for instance – may find some consolation in this belief.