In a general sense, justice means the giving of rights to the deserving without any discrimination. It is unjust to deprive the deserving of their rights. Discrimination, that is, granting some people their rights while depriving some others of theirs is unjust. If a teacher gives all his students grades lower than what they deserve, he has behaved unjustly.
In the same way, by giving some of them the grades they deserve according to their merit, and some others lower grades than what they deserve, again he shall be, behaving unjustly. In one respect, justice accompanies equality, which is considering all people equal, and not discriminating among them.
Justice is a requirement for equality, that is, to fulfil the right of every one according to his deserts without any discrimination. Equality does not mean «granting» the same amount to all people regardless of their deserts or the scales of their deserts. If so it would be unjust and signify cruelty. Equality in deprivation is cruelty too. That is, preventing all people from obtaining their deserts, is also a sort of cruelty.
Therefore, God's Justice means that He provides his creatures with blessings according to their capability. The lack of anything in any creature is due to the fact that because of the total conditions and circumstances in which the creature is, it does not possess the possibility and capacity of having the thing it lacks.
It would be unjust if some creatures with certain capabilities were deprived of their full deserts: however, in actuality they are justly granted God's Grace according to their merit. Among creatures, man possesses unique potentials and skills, His motivations which direct him to work and be active are not limited as is the case with other creatures.
In contrast with animals, whose instincts are limited to their environment, human instincts go beyond the limits of this world, being characterized by an everlasting nature. What affects man's deeds are his supreme moral, scientific, artistic, religious and divine motivations. Man often sacrifices his natural, material and animal life for his supreme, human aims.
According to the Qur’an's interpretation, man regulates his conduct on the basis of «faith and pious deeds» through which he wishes for eternal life and God's contentment. Man possesses an intense capacity for thought and the instincts leading him towards it and he desire eternity.
All these reveal a sort of potential in man for an everlasting life. In other words, they reveal the spirituality, and immaterial quality of man's soul. They compare man in this world to a fetus in the womb where it is provided with circulatory, respiratory, nervous, optic, auditory and genital systems which are in accord with the post- natal life but not with the condition of the womb and the temporary nine months life there.
Although man receives benefits from faith and pious deeds in this life, these are merely consequential. Faith and pious deeds suggest seeds which grow and flourish only in a happy, everlasting life, that is, they will realize their full meaning for and in eternal life.
Not only can man soar above nature and scatter nonmaterial seeds in a system based on faith and pious deeds, but when one deviates (from the true path), which is termed as domains of atheism and depravity in the Qur’an, the consequences of one's deeds also go beyond animal limitations and ordinary physical relationships. One's deeds become spiritual and eternal but in a deviant way.
Thus one becomes deserving of a sort of eternal life in which one unfortunately suffers pain and agony. In religious terms, one incurs eternal hell-fire. If one deviates from faith and pious deeds, one descends even below animal life and falls to the lowest status. According to the Qur’an's interpretation,
إِنْ هُمْ إِلَّا كَالْأَنْعَامِ بَلْ هُمْ أَضَلُّ سَبِيلًا
“They are like beasts, and even more misguided” (25:44).
Those who follow the bases of faith and pious deeds and those who deviate from them can be compared to students, of whom the first group does their assignments conscientiously, while the second waste their time playing. If a teacher did not grade all of them, it would be unjust. In the same manner, if there were no eternal life in which the faithful and pious would be rewarded and those who have followed the path of infidelity and depravity would be punished, both would be deprived of just deserts and this would be oppressive and unjust.
To show this more clearly, we say that God has asked people to be faithful and benevolent. Accepting this, a group of people accords their thoughts, morals and deeds with their beliefs. Rejecting this, another group follows evil deeds and corruption. We notice that the order of this world does not always reward the benevolent or punish the corrupt precisely. Man sometimes dies before receiving the reward of his righteous deeds; therefore, there should be another place to fully reward the benevolent and punish the wrongdoers, otherwise it would be unjust of God.