Belief in the Hereafter is belief in the Unseen, which is known only to the Omnipotent, Omniscient Creator. Allah (Exalted be He) says:“ Did ye then that We had created you in jest, and that ye would not be brought back to us (for account)?” (Qur'an 23:115).
“ Not without purpose did We create heaven and earth and all between! That were the thought of the unbelievers! But woe to the unbelievers because of the Fire of Hell! Shall We treat those who believe and work deeds of righteousness, the same as those who do mischief on earth? Shall We treat those who guard against evil, the same as those who turn side from the right?” (Qur'an 38:27-28).
“ Shall We then treat the people of faith like the people of sin? What is the matter with you? How judge ye?” (Qur'an 68:35-36).
In fact life would be absurd if there was no Day of Judgment on which all the dead will be resurrected and questioned about their deeds in this earthly life.
This can be easily realized by everybody without the need for material evidence. In this world, there are many examples in which divine justice is not fulfilled and we naturally come to the conclusion that there should be some world or life other than this transient one in which all unsettled issues and deeds of injustice are brought forward in the Divine Court of Justice, and the righteous and the wicked receive their just reward or punishment. Such a Day of Judgment is extremely necessary, for we see many cruel or wicked people who are devoted to sins and wrongdoing, and yet they lead a happy comfortable life without getting their due punishment On the other hand, there are many righteous people who lead a miserable life during which they suffer from oppression, humiliation, poverty or homelessness and at last die without being requited. Is all this consistent with Divine Justice? Not in the least. Then there must be such an inevitable day devoted to a lasting settlement of all accounts.
But many people are blinded to this fact owing to various factors such as whims, covetousness, lack of belief and deviation from the truth.
Thus, everything we do in this world, every intention we have, every move we make, every thought we entertain, and every word we say, all will be we counted and kept in accurate records. On the Day of Judgment, they will be brought up. People with good records will be generously rewarded and warmly welcomed to the Heaven of Allah, where there is eternal and perfect bliss, and those with bad records will be punished and cast into Hell. That is, in a word, the Day of Judgment and final settlement of all accounts.