Faith in the hereafter is one of the most important pillars of faith. In the first surah of the Qur'an, after His attributes, the "All-Merciful" and the "the Most Merciful", God states that "He is the King of the Day of Judgement" (Surat al-Fatiha: 3).
In the third verse of the next surah, it is stated that believers are "...those who have faith in the Unseen..." (Surat al-Baqarah: 3)
This concept of "the Unseen" also includes rising from the dead after death, the Day of Resurrection, paradise and hell, in brief, everything related to the Hereafter. Indeed, in the next verse, the 4th verse of Surat al-Baqarah, with the words "...they are certain about the Hereafter", a special emphasis is given to faith in the Hereafter.
Belief in the Hereafter is a sign of true faith, and as such is very important. The sort of faith in the Hereafter as defined by the Qur'an provides strong evidence for the sincerity and truthfulness of a believer. One having faith in the Hereafter has already reposed unconditional faith in God, in His Book and in His messenger. Such an individual knows that God has power over all things and that His words and promises are true. Consequently, he never harbours doubts about the Hereafter. Before seeing and witnessing these facts, he puts his faith in them as if he has already seen them. This is the natural consequence of the faith and trust he puts in God and the wisdom granted to him. Furthermore, an unshakeable faith in the Hereafter, purified of all forms of doubts, embraces faith in the existence of God as well as in His attributes, as explained in the Qur'an, and complete trust in and submission to Him. This faith also makes one know God and appreciate Him as is proper. This is the type of faith God considers to be precious.
From the foregoing, it is clear that having true and complete conviction rests upon a committed faith in the Hereafter. In many parts of the Qur'an, there are references to disbelievers' denial of the Hereafter and their indecision about its realisation. In fact, the majority of these are people who believe in the existence of God. However, what misleads them most is not the issues pertaining to the existence of God but to His attributes. Some believe God initially created everything and then left human beings to their own devices. Some, on the other hand, hold that God created man, but that it is the individual himself who determines his own fate. Another group maintains that God does not know the inner thoughts and secrets of man. Some others believe in the existence of God, but reject the idea of religion. The holders of this last conviction are defined in the Qur'an as follows:
They do not measure God with His true measure when they say, 'God would not send down anything to a mere human being.' (Surat al-An'am:91)
Consequently, rather than a total denial of the existence of God, "not measuring God with His true measure" and accordingly, the denial of the Hereafter, underlie faithlessness. Indeed, the proportion of people refusing to accept the existence of the Creator is rather low and many of them often entertain doubts about their convictions. That is why in the Qur'an, there is not much mention of people who deny God. Conversely, one finds extensive reference to people who ascribe partners to God and deny rising from the dead, the Judgement Day, Paradise, Hell and to all the details and rationales pertaining to faith in the Hereafter.
Although the Hereafter is a fact which cannot be perceived through the five senses, God created it along with countless pieces of evidence so that our minds might easily have a grasp of it. As a matter of fact, as a requisite for passing the test of this world, one should perceive this fact, not through the five senses, but with wisdom and as a matter of conscience. Any average person, after some contemplation, easily recognises that everything in his environment, including himself, could not have come into existence as a result of pure coincidence but rather by the exercise of the superior might, knowledge, will and control of a Creator. Then, he consequently comprehends that the creation of the Hereafter is simple for God and that it is the most natural and rational consequence of this world. Furthermore, he realises that God's wisdom and justice entail the existence of the Hereafter.
Although this is so apparent, one who is rebellious against the commandments of God, would dislike the idea of rising from the dead. As one who spends his life on satisfying his vain desires, he would not be willing to stand before God to give an account of the deeds he engaged in throughout his life. That is why, despite having a thorough grasp of the existence of God, he would choose to suppress the voice of his conscience and deceive himself. Being confined in such a dimension, a disbeliever starts to make unwise, inconsistent and irrational comparisons without any long-term considerations, just to deny the resurrection and the Hereafter:
He makes likenesses of Us and forgets his own creation, saying, 'Who will give life to bones when they are decayed?' (Surah Ya sin: 78)
However, this question, designed merely to escape reality and bolster self-deceit, has an explicit answer:
Say 'He who made them in the first place will bring them back to life. He has total knowledge of each created thing.' (Surah Ya sin: 79)
In the Qur'an, God makes it clear that the making of such inconsistent comparisons is an attribute peculiar to disbelievers:
Evil are the ways of those who do not have faith in the Hereafter. But most sublime are the ways of God. He is the Almighty, the All-Wise. (Surat an-Nahl: 60)
Some, on the other hand, attempt to justify their stance by providing some so-called explanations:
They will say, 'Are we to be restored to our former state? When we have become decayed, worm-eaten bones?' They say, 'That will clearly be a fruitless restoration!' (Surat an-Nazi'at: 12)
In fact, despite being convinced about it, they do not hesitate to confess that the existence of the Hereafter does not fit in with their goals in life.
The disbeliever curtails his own wisdom by his own will. Seeing the irrationality of his own claims, he still treats this issue with sentimental obstinacy and goes to great lengths to find psychological satisfaction in it:
They swear by God with their most earnest oaths that God will not raise up those who die, when, on the contrary, it is a binding promise on Him; but most people do not know it. (Surat an-Nahl: 38)
Taking their whims and desires as their gods, these people utter vain words to ease their consciences and then take refuge in them. God describes the nature of these people who deny the existence of the Hereafter:
We created many of the jinn and mankind for Hell. They have hearts they do not understand with. They have eyes they do not see with. They have ears they do not hear with. Such people are like cattle. No, they are even further astray! They are the unaware. (Surat al-A'raf: 179)
In another part of the Qur'an, the situation of these people is described as follows:
Have you seen him who takes his whims and desires to be his god – whom Allah has misguided knowingly, sealing up his hearing and his heart and placing a blindfold over his eyes? Who then will guide him after Allah? So will you not pay heed? (Surat al-Jathiyya, 23)
They say, 'There is nothing but our existence in the world. We die and we live and nothing destroys us except for time.' They have no knowledge of that. They are only conjecturing. (Surat al-Jathiyah: 23-24)