The question of whether or not there is life after death does not fall under the field of science, because science is only concerned with the classification and analysis of recorded data. Moreover, man has been busy with scientific enquiries and research, in the modern sense of the term, only for the last few centuries, while he has been familiar with the idea of life after death since times immemorial. All the prophets of God called their people to worship God and to believe in life after death. They laid so much emphasis on the belief in life after death that even a slight doubt in it meant denying God and made all other beliefs meaningless. The very fact that all the prophets of God have dealt with this metaphysical question so confidently and uniformly - the gap between their ages being thousands of years - goes to prove that the source of their knowledge of life after death, as proclaimed by them all, was the same, that is, Divine revelation.
We also know that these prophets of God were greatly opposed by their people, mainly on the issue of life after death, as their people thought it impossible. But in spite of that opposition, the prophets won many sincere followers. The question arises, what made those followers forsake the established beliefs, traditions and customs of their forefathers, regardless of the risk of being totally alienated from their own community? The simple answer is that they made use of their faculties of mind and heart and realized the truth.
Did they realize the truth through experiencing it? Not so, as the perceptual experience of life after death is impossible. Actually, God has given man, besides perceptual consciousness, rational, aesthetic and moral consciousness too. It is this consciousness that guides man regarding realities that cannot be verified through sensory data. That is why all the prophets of God, while calling people to believe in God and the life hereafter, appealed to the aesthetic, moral and rational sides of man. For example, when the idolaters of Makkah denied even the possibility of life after death, the Qur'an exposed the weakness of their stand by advancing very logical and rational arguments in support of it:
And he has coined for us a similitude, and has forgotten the fact of his creation, saying: Who will revive these bones when they have rotted away? Say: He will revive them who produced them at the first, for He is the Knower of every creation, Who has appointed for you fire from the green tree, and behold! you kindle from it. Is it not He who created the heavens and the earth, able to create the like of them? Yes, and He is indeed the Supreme Creator, the All-Knowing.
At another occasion, the Qur'an very clearly says that the disbelievers have no sound basis for their denial of life after death. It is based on pure conjectures:
They say, 'There is nothing but our present life; we die, and we live, and nothing but Time destroys us.' Of that they have no knowledge; they merely conjecture. And when Our revelations are recited to them, their only argument is that they say, 'Bring us our father, if you speak truly.' (Al-Qur'an 45:24-25)
Surely God will raise all the dead. but God has His own plan of things. A day will come when the whole universe will be destroyed and then again the dead will be resurrected to stand before God. That day will be the beginning of the life that will never end, and that Day, every person will be rewarded by God according to his good and evil deeds.
The explanation that the Qur'an gives about the necessity of life after death is what the moral consciousness of man demands. Actually, if there is no life after death, the very belief in God becomes irrelevant, or even if one believes in God, that would be an unjust and indifferent God: having once created man only to be unconcerned with his fate. Surely, God is just. he will punish the tyrants whose crimes are beyond count: having killed hundreds of innocent persons, created great corruptions in the society, enslaved numerous persons to serve their whims, and so forth. Man, having a very short span of life in this world, and this physical world, also, not being eternal, punishments or rewards equal to the evil or noble deeds of persons are not possible here. The Qur'an very emphatically states that the Day of Judgment must come and God will decide about the fate of each soul according to his or her record of deeds:
Those who disbelieve say: The Hour will never come unto us. Say: Nay, by my Lord, but it is coming unto you surely. (He is) the Knower of the Unseen. Not an atom's weight, or less than that or greater, escapes Him in the heavens or in the earth, but it is in a clear Record. That He may reward those who believe and do good works. For them is pardon and a rich provision. But those who strive against our revelations, challenging (Us), theirs will be a painful doom of wrath. (Al-Qur'an 34:3-5)
The Day of Resurrection will be the Day when God's attributes of Justice and Mercy will be in full manifestation. God will shower His mercy on those who suffered for His sake in the worldly life, believing that an eternal bliss was awaiting them. But those who abused the bounties of God, caring nothing for the life to come, will be in the most miserable state. Drawing a comparison between them the Qur'an says:
"Is he, then, to whom we have promised a goodly promise the fulfillment of which he will meet, like the one whom We have provided with the good things of this life, and then on the Day of Resurrection he will be of those who will be brought arraigned before God?" (Al-Qur'an 28:61)
The Qur'an also states that this worldly life is a preparation for the eternal life after death. But those who deny it become slaves of their passions and desires, and make fun of virtuous and God-conscious persons. Such persons realize their folly only at the time of their death and wish in vain to be given a further chance in the world. Their miserable state at the time of death, and the horror of the Day of Judgment, and the eternal bliss guaranteed to the sincere believers are very beautifully mentioned in the following verses of the Qur'an.
"Until, when death comes unto one of them, he says, 'My Lord, send me back, that I may do right in that which I have left behind!' But nay! It is but a word that he speaks; and behind them is a barrier until the day when they are raised. And when the Trumpet is blown there will be no kinship among them that day, nor will they ask of another. Then those whose scales are heavy, they are successful. And those whose scales are light are those who lose their souls, in hell abiding, the fire burns their faces and they are glum therein." (Al-Qur'an 23:99-104)
The belief in life after death not only guarantees success in the Hereafter, but also makes this world full of peace and happiness by making individuals most responsible and dutiful in their activities.
Think of the people of Arabia. Gambling, wine, tribal feuds, plundering and murdering were their main traits when they had no belief in a life hereafter. But as soon as they accepted the belief in One God and life after death, they became the most disciplined nation of the world. They gave up their vices, helped each other in hours of need, and settled all their disputes on the basis of justice and equality. Similarly, the denial of life after death has its consequences not only in the Hereafter, but also in this world. When a nation as a whole denies it, all kinds of evils and corruptions become rampant in that society and ultimately it is destroyed. The Qur'an mentions the terrible end of 'Aad, Thamud and the Pharaoh in some detail:
"(The tribes of) Thamud and 'Aad disbelieved in the judgment to come. As for Thamud, they were destroyed by the lightning, and as for 'Aad, they were destroyed by a fierce roaring wind, which he imposed on them for seven long nights and eight long days, so that you might see the people laid prostrate in it as if they were the stumps of fallen down palm trees.Now do you see remnant of them? Pharaoh likewise and those before him and the subverted cities. They committed errors and those before him, and they rebelled against the Messenger of their Lord, and He seized them with a surpassing grip. Lo, when the waters rose, We bore you in the running ship that We might make it a reminder for you and for heeding ears to hold. So when the Trumpet is blown with a single blast and the earth and the mountains are lifted up and crushed with a single blow, then on that day, the Terror shall come to pass, and the heaven shall be split, for upon that day it shall be very frail. Then as for him who is given his book in his right hand, he shall say 'Here, take and read my book! Certainly I thought that I should encounter my reckoning.' So he shall be in a pleasing life in a lofty garden, its clusters nigh to gather.Eat and drink with wholesome appetite for what you did long ago, in the days gone by.But as for him who is given his book in his left hand, he shall say: 'Would that I had not been given my book and known my reckoning! Would it had been the end! My wealth has not availed me, my authority is gone from me.'" (Al-Qur'an 69:4-29)
Thus, there are very convincing reasons to believe in life after death.
First, all the prophets of God have called their people to believe in it.
Secondly, whenever a human society is built on the basis of this belief, it has been the most ideal and peaceful society, free of social and moral evils.
Thirdly, history bears witness that whenever this belief is rejected collectively by a group of people in spit of the repeated warning of the Prophet, the group as a whole has been punished by God, even in this world.
Fourthly, moral, aesthetic and rational facilities of man endorse the possibility of life after death.
Fifthly, God's attributes of Justice and Mercy have no meaning if there is no life after death.