Belief in the Hereafter is one of the six pillars of Islamic belief required of a Muslim in order to complete his faith.
The Prophet informed us about the events of the unseen which will occur after death. This fundamental belief is only completed when one has firm faith in his heart in all those matters about which the Prophet informed us.
Ahlus-Sunnah Wal-Jamaa’ah (mainstream Muslims) believe in all of these events, whereas the people of innovation refuse to accept events such as the questioning in the grave, the bliss and the trials of the grave, the punishment in the grave, the passing over the Siraat (the Bridge set over Hell), and the setting of the scales.
The reason for their denial is that, in their estimation, these matters cannot be proven by mere intellect. Since they consider their intellect to be the judge over everything, they do not believe in matters which are beyond their comprehension.
Materialists refuse to believe in anything which they do not feel. Our answer to this attitude is that our inability to sense the existence of certain things does not justify our denial of the very existence of those things. Certitude through news from an authentic person is as good as the certitude by seeing and feeling. Since the honesty of Prophet Muhammad in conveying the Divine Message revealed to him has been established for us, we –believers –firmly believe in everything he told about the unseen, including the Hereafter. Belief in the hereafter entails the following:
(A) Belief in Events of the Grave:
Ahlus-Sunnah Wal-Jamaa’ah believe in the trial of the grave. The Arabic word for trial is 'Fitnah', which linguistically means to place gold in fire in order to remove its impurities; this word was thus later used in the sense of testing and trying.
The Quranic evidence concerning this issue is in the following verse in which Almighty Allah describes the punishment of the people of Fir'awn (Pharaoh); Allah, the Most Exalted, Says (what means): {The Fire: they are exposed to it morning and evening. And the Day the Hour appears [it will be said]: 'Make the people of Pharaoh enter the severest punishment.'} [Quran 40:46]
Also, the Prophet said: "The grave is either a garden from the Gardens of Paradise, or a pit from the pits of Hell." [At-Tirmithi]
(B) Events of the Day of Judgement
After the duration of this earth is over, Allah will command Israfeel [the Angel in charge of blowing the Trumpet] to blow it. At the first blowing, all the inhabitants of the heavens and the earth will fall unconscious, except those for whom Allah Wills otherwise. Then, the earth will be flattened and the mountains will be made into floating sand dunes. In short, everything will occur that Allah has informed us about in His Book, especially in chapters 81 and 82 of the Noble Quran.
Then, Allah will command the skies to pour rain. This rain will resemble the sperm of men. People will then be resurrected from their graves. This process will start from their vertebral column. The entire body of a person decays after his death except the lower end of the vertebral column. This process of resurrection will continue until they are transformed back into their original shape and bodies. Allah will then command Israfeel to blow the Trumpet for the second time, upon which people will rise from their graves alive. The disbelievers and the hypocrites will then be regretful and will say (what means): "…Woe to us! Who has raised us up from our sleeping place?" [Quran: 36:52] Whereas the believers will say (what means): "…This is what the Most Merciful had promised, and the Messengers spoke the truth." [Quran 36:52]
Then, the angels will drive all of them naked, uncircumcised, and barefooted to the place of Hashr (Gathering).
The first one to be dressed on that Day will be Prophet Ibraheem, may Allah exalt his mention. At the place of Gathering, the sun will descend close to the heads of people, and their sweat will engulf them. It will be up to the ankles of some of them, up to the knees of others, up to the chests of others, and up to the necks of others. The level of their sweat will be in accordance with their deeds.
Some people on that Day will be sheltered by the shade of the Throne of Allah. When the conditions become unbearable for people, and the despair increases greatly, people will ask Allah to allow His Messengers and Prophets to intercede for them and save them from their distress. Every Messenger and Prophet will advise the people to go to the Prophet who came after him, until they come to our Prophet Muhammad . He will respond by saying that he is the appropriate person for it. He will intercede for them, which will result in the beginning of Judgement.
C- The Balances
The balances will then be erected, and the deeds will be weighed. These balances will be real and will have pans and needles. Allah, the Exalted and Glorified, will give the deeds of the creatures a material existence that will have weight. The good deeds will be placed in one pan and the evil deeds in the other, as Allah informs us in the Quran, Saying (what means):
"And We shall set up balances of justice on the Day of Resurrection, then none will be dealt with unjustly in anything. And if there be the weight of a mustard seed, We will bring it. And Sufficient are We to take account." [Quran 21:47]
D-The Records
This will be followed by the disclosure of the record of deeds. He who will receive his record in his right hand will have an easy reckoning. He will return to his family in happiness.
However, he who will receive his record from behind and in his left hand, will seek death on that Day, as he will be thrust into Hellfire. He will be full of regrets on that Day and will wish that he was not handed his record or that he had not known about it. Allah Says (what means): "Then as for him who is given his record in his right hand. He will be judged with an easy account. And return to his people in happiness. But as for he who is given his record behind his back. He will cry out for destruction. And [enter to] burn in a Blaze." [Quran 84:7-12]
All the events that are bound to occur after death and on the Last Day, like reward and punishment, Paradise and Hell, the Reckoning and other events are mentioned in detail in the Divine revelations and in narrations from the Prophets. They are also available in the knowledge which the Prophet has left us as his inheritance; whoever wishes to seek it, will find it.