—considering that what is inferred from it is that some of the believing, righteous, oppressed, beloved, striving, compassionate, and courageous servants of Allah certainly gain authority over the Earth in the future, and the Mahdi is a perfect example of such servants, according to the descriptions mentioned for him in the widely transmitted reports from the Prophet . Therefore, his authority over the Earth in the future is certain, according to Allah’s promise in the Quran; as He has said: ﴿يَا أَيُّهَا النَّاسُ إِنَّ وَعْدَ اللَّهِ حَقٌّ﴾[1]; “O people! Undoubtedly, the promise of Allah is true,” and: ﴿وَعْدَ اللَّهِ ۖ لَا يُخْلِفُ اللَّهُ وَعْدَهُ﴾[2]; “This is the promise of Allah, and Allah never breaks His promise,” and: ﴿فَلَا تَحْسَبَنَّ اللَّهَ مُخْلِفَ وَعْدِهِ رُسُلَهُ﴾[3]; “So do not suppose that Allah would break His promise to His Prophets,” and: ﴿إِنَّمَا تُوعَدُونَ لَصَادِقٌ﴾[4]; “Indeed, what you are promised is certainly true,” and: ﴿إِنَّمَا تُوعَدُونَ لَوَاقِعٌ﴾[5]; “Indeed, what you are promised certainly happens.” Based on this, it is appropriate that belief in the certainty of the Mahdi’s advent—as Allah’s caliph on the Earth and a man from the Ahl al-Bayt of the Prophet , who fills the Earth with justice and equity by establishing the perfect and pure Islam—be considered one of the well-established matters of Islam and a point of unanimous agreement among Muslims, so that it may serve as a basis for their unity in the future.

[The Non-Appearance of the Mahdi on the Earth and the Necessity of His Appearance]

However, the Earth has not yet been filled with justice and equity, and this means that the Mahdi has not yet appeared, and those who think that he has are mistaken[6]. Of course, his appearance does not merely mean people’s access to him, but rather his authority over the Earth; as Allah Almighty has said: ﴿يَا قَوْمِ لَكُمُ الْمُلْكُ الْيَوْمَ ظَاهِرِينَ فِي الْأَرْضِ﴾[7]; “O people! Today, dominion belongs to you while you are manifest on the Earth,” and: ﴿فَأَيَّدْنَا الَّذِينَ آمَنُوا عَلَى عَدُوِّهِمْ فَأَصْبَحُوا ظَاهِرِينَ﴾[8]; “Then We helped those who believed against their enemy, so they became manifest.” It is clear that his appearance—meaning his authority over the Earth following people’s access to him—is necessary for the fulfillment of the promise of Allah and His Prophet; because what is inferred from Their promise is that, before the Mahdi’s appearance, the Earth will be filled with oppression and will not be filled with justice. This means that Allah’s sovereignty over the Earth is not established before the Mahdi’s appearance;