Mahdi (as) is a messianic figure in Islamic eschatology who is believed to appear at the end of times to rid the world of evil and injustice. He is said to be a descendant of Prophet Muhammad (PBUH& HP) who will appear while Jesus Christ (Prophet Isa-ibni Maryam) accompanying him and will lead the believers to rule the world and fill it with justice and peace. This is what the Quran says:

 And We wanted to confer favour upon those who were oppressed in the land and make them leaders and make them inheritors. (Al-Qasas 28:5)

Who is Mahdi (as)? 

The name Mahdi is derived from the Arabic root h-d-y, commonly used to mean "divine guidance". Though Imam Mahdi features in both Shia and Sunni understandings of Islam, they differ in his attributes and status. Among Twelver Shi’as, Mahdi is believed to be the son of the eleventh Imam, Imam Hasan al-Askari (d. 874), and is said to have been on divine occultation (ghaybat) by God’s will. However, the Sunnis assert that he (Imam Mahdi) is a descendant of Lady Fatimah (SA), the daughter of the Prophet Muhammad, and it is unknown whether he was born or not.

What is the View of Muslims About Mahdi (as)?

According to our belief, one of the most extraordinary acts of worship is to wait for the promised saviour, and this waiting means trying to provide the conditions for his reappearance.

In the Shi'a Islam, or the school of Ahlul-Bayt, the eschatological Mahdi was commonly given the epithet al-Qa'im, which can be translated as “he who will rise”, signifying his rise against tyranny in the end of all times. Distinctively Shi'a is the notion of the temporary occultation of Imam Mahdi, whose life has been prolonged by God’s will.

As in above mentioned, the Sunnis also believe in the promised Mahdi and many hadiths about him have been narrated in their books. Abu Dawood quotes Prophet Muhammad (PBUH & HP) as saying: " Mahdi will be from my household, from the descendants of Fatimah”. And another hadith states: “Even if only one day remains [until the doomsday], God will lengthen this day until He calls forth a man from me, or from the family of my house, his name matching mine and his father's name matching that of my father. He will fill the Earth with equity and justice just as it had previously been filled with injustice and oppression”. (Furnish, 2005, p. 14) According to narrations before the arrival of Imam Mahdi, the earth would be filled with chaos. While divisions and civil wars, moral degradation, and worldliness would be prevalent among people, injustice and oppression would be rampant throughout the world. The Dajjal (The Anti-Christ) would appear and will spread decadence and corruption in the world. With an army bearing black banners, which would come to his aid from the east, Imam Mahdi would confront the Dajjal. Jesus would pray behind Imam Mahdi and then will kill the Dajjal. The Sufyani, another representative of the forces of the dark, also features in the traditions. He will rise in Syria before the appearance of Imam Mahdi. When the latter appears, the Sufyani, along with his army, will either be swallowed up en-route to Mecca by the earth by God's command or defeated by Imam Mahdi.

What Role does he have in the Future of Humanity

In Imamiyyah (Twelver Shiism), the largest Shi’a branch, believing in the messianic imam is not merely a part of the creed, but is the pivot. For the Twelver Shi'a, Imam Mahdi was born but disappeared after a while, and he would remain hidden from humanity until he reappears to bring justice to the world at the end of time, a doctrine known as the Occultation. This Imam on occultation is the twelfth imam, named Muhammad, son of the eleventh Imam, Hasan al-Askari. According to the Twelvers, the Mahdi was born in Sammara around 868, though his birth was kept hidden from the public. He lived under his father's care until 874 when the latter was killed by the Abbasids. 

Shi'a scholars have argued that the prolonged lifespan of Imam Mahdi Mahdi is not at all unreasonable given the longevity of  the Prophet Noah, Khidr and Jesus, as well as secular reports about long-lived people. According to scholars Imam Mahdi is viewed as the restorer of true Islam, and the restorer of other monotheistic religions after their distortion and abandonment. He establishes the kingdom of God on earth and Islamizes the whole world. As a matter of fact, in their true form, it is believed, all monotheistic religions are essentially identical to Islam as "submission to God." It is in this sense, that one should understand the allegation that al-Mahdi will impose Islam on everyone. His rule will be paradise on earth, which will last for several years until his decease.[1]

References:

1. (Sachedina, 1981, p. 176-178)

Ramadan is one of the most important months in the Islamic calendar, during which Muslims perform fasting (Sawm), one of the key practices in the religion of Islam. However, aside from being a month of fasting, Ramadan provides Muslims with the opportunity to engage more in their routine religious activities and have a fuller experience of an Ideal Islamic life. There is more to this month, then, that makes it a special time. Let’s see.

1. Ramadan is a Gift from Allah

Ramadan is a door that has been opened to get Muslims nearer to Allah and to feel His presence more in their lives. This is the time when Allah forgives most and rains down His blessings more than any other time which can wipe away our sins and mistakes [i]. If we knew the real value of this month and were aware of all its rewards, we would wish every month to be Ramadan, as Prophet Muhammad (PBUH&HP) believed [1].

We are so close to Allah in this month and so occupied with his divine remembrance that no time will be left for us to think or do what is not good for us, or what is against Allah’s command. So the inward and outward evil stay far from us in this month of mercy, and it has been promised by Prophet Muhammad (PBUH&HP) that in Ramadan, “the gates of hell are sealed, and the gates of heaven are wide open, and the devils are chained” [1].

2. Ramadan is the Month of Salvation and Forgiveness

Ramadan begins with mercy, continues to bring forgiveness from Allah and ends in granting our wishes and salvation from what has contaminated our souls [2]. It is a time to think about our past mistakes and to make up for them, to make them right.

One of the prominent attributes of Allah is His excessive forgiveness and mercy which reveals itself manifestly and in a fuller sense in the month of Ramadan. It is as if Allah has held us tightly in His embrace and washed away whatever has separated us from Him, and we would be like a child who has just been born, like a soul united with its source. So, when is a better time to be forgiven than this month? [3].

3. Ramadan is the Spring of the Quran and Celebration of the Nights of Qadr

In this beautiful month, the whole content of the Quran was revealed to the heart of Prophet Muhammad (PBUH&HP) in an immediate revelation [ii], [4] & [5]. Therefore, this month can be considered as the birth of the holy Quran [iii], and Muslims celebrate this birth through dedicating more time and attention to this holy book.

Thus, reading the Quran with careful consideration and pondering on its deep meanings is highly recommended during the month of Ramadan and it is considered to be more rewarding, to the extent that reading one verse of the Quran is equaled to reading all of it [iv]& [v]. In the month when Allah is closer to us more than ever, He desires to speak to us through the Quranic words, just as we speak to Him, through our prayers.

What Are the Nights of Qadr?

There are three nights in this month [vi], called the nights of Qadr [vii], one of which is considered to be the night when Quran was revealed to the heart of Prophet Muhammad (PBUH&HP) in an immediate revelation by the Archangel Gabriel. However, we are not sure which of these nights is exactly the night of Qadr. Therefore we commemorate all of these three nights.  

According to the Quran: “The Night of Qadr is better than a thousand months”(97:3); in other words, the reward of any good deed in this night is a thousand times more than any other night or occasion [8].  Muslims celebrate this night by staying awake throughout the night until the time of Dawn prayer (Salat al-Fajr), supplicating to Allah and asking for His forgiveness of their past deeds and guidance for their future actions.

The night of “Qadr is a celebration to commemorate the arrival of the final guidance for humans. It is a tribute to the commencement of the message revealed to mankind by their Creator, a message which shows them the way to achieve happiness in both worlds” [8].

Aside from being the night in which our sins are forgiven, according to some narrations (Hadith), the night of Qadr is also the night of our destiny; the night in which our fate in the next year is foreseen by Allah [viii], [9].

Finally, life is too short, and chances are slipping away from your hands like spring clouds [10]. Ramadan is one of these chances, to look back and build a better future. It is a starting point, or shall we say a turning point! So embrace this holy month.  

Notes:
[i] Prophet Muhammad (PBUH&HP) said: “The month of Ramadan is the month of Allah, and a month in which Allah highlights the virtues and wipes away the sins, this is the month of blessing” [1].

[ii] It is believed that there are two kinds of revelation for the Quran, the immediate revelation that occurred in one of the nights of Qadr and the gradual revelation which sent down to Prophet Muhammad (PBUH&HP) in the span of twenty-three years of his prophethood [11]. 

[iii] Imam Baqer (AS) said: “There is a spring for everything, and the spring of Quran is the month of Ramadan”. [6]

[iv] Imam Reza (AS) said: “whoever read a verse of Allah’s book [Quran] in the month of Ramadan, it would be equal to his/her reading of the whole of Quran in other months” [7].

[v] Prophet Muhammad (PBUH) said: “Read Quran abundantly during the month [of Ramadan]” [7].

[vi]  19th, 21st and 23rd of Ramadan.

[vii]. Qadr literally means measure.

[viii]. Note that the concept of destiny or Qadr is not in conflict with human beings freedom of choice in Islam. For more information see Men and Destiney by Murtada Mutahari.

References:

1. Bihar al-Anvar, vol.93, p.340, 346 & 348.
2. Usul al-Kafi, vol.4, p.67.
3. Sheikh al-Sadugh, Amali, p.53.
4. (44: 3), (97:1), (2:185)
5. For further information, see: Al-Mizan, vol. 8, pp. 130-134; vol. 2, pp. 14-23; vol. 13, pp. 220-221.
6. Usul al-Kafi, vol.2, p.360, Hadith no. 10.
7. Sheikh al-Sadugh, Fazail al-Ashhar al-Salasah (the benefits of three months), p. 95.
8. Ramadan
9. Muhammad ibn Hassan Tussi, Tahdib al-Ahkam, vol.4, p.332.
10. Imam Ali (AS), Nahj al-Balaghah, wisdom no. 21.
11. Shaykh as-Saduq, A Shi'ite Creed, p. 60.