Term used in Judaism for the expected returning leader and liberator of the religion. The character named Messiah should be of the line of King David, be a king and characterized by the priestly tradition starting with Moses. Messiah's mission was to free Israel from foreign bondage and bring the country back to former glory. In Isaiah 53 (see excerpt below) Messiah is also described as a suffering servant.
The term comes from Hebrew "mashiah", which is derived from the term "hameshiach", which was the title given to the king of Judah, indicating the sacred office of the king. "Hameshiach" can be translated with "the Lord's anointed".
The origin of the ideology of the Messiah has its roots, both historically and symbolically, with the rule of King David in the early 10th century BCE. King David formalized some central religious structures and he established Jerusalem as the cult centre of the Hebrew religion. But most important, he made Israel and Judah for some decades into the strongest state of the region, defeating most of the neigbouring peoples.
The ideology of Messiah grew strong in the times following the Babylonian Exile (6th century BCE), when the Jews realized that Israel was lost, and the opponents appeared to be invincible. This idea of Messiah was one of human character, but with extraordinary powers.
Several hundred years later, with the Roman occupation of Israel, many sects within Judaism developed a more mystical notion of Messiah. A character called "Son of Man" was to descend from heaven and save Israel. And in the same epoch there were numerous people claiming to be Messiah.
After the Roman destruction of the Second Temple of Jerusalem in 70 CE, the hardship that the Jews experienced (exile and persecution) intensified the ideology of Messiah, and varying versions allowed him to be a human being of special qualities. And just like before, there were many men, often in regions far away from the original Israel, who claimed to be Messiah.
In many modern Jewish orientations, there are ideas that there can be a messianic future (a situation where Israel is restored, and Jews live in peace and safety) without a personal Messiah.
THE BOOK OF THE PROPHET ISAIAH, Chapter 53
1 Who hath believed our report? and to whom is the arm of the LORD
2 For he shall grow up before him as a tender plant, and
as a root out of a dry ground: he hath no form nor comeliness; and
when we shall see him, there is no beauty that we should desire him.
3 He is despised and rejected of men; a man of sorrows, and
acquainted with grief: and we hid as it were our faces from him; he
was despised, and we esteemed him not.
4 Surely he hath borne our griefs, and carried our sorrows: yet we
did esteem him stricken, smitten of God, and afflicted.
5 But he was wounded for our transgressions, he was bruised for our
iniquities: the chastisement of our peace was upon him; and with his
stripes we are healed.
6 All we like sheep have gone astray; we have turned every one to
his own way; and the LORD hath laid on him the iniquity of us all.
7 He was oppressed, and he was afflicted, yet he opened not his
mouth: he is brought as a lamb to the slaughter, and as a sheep before
her shearers is dumb, so he openeth not his mouth.
8 He was taken from prison and from judgment: and who shall declare
his generation? for he was cut off out of the land of the living: for
the transgression of my people was he stricken.
9 And he made his grave with the wicked, and with the rich in his
death; because he had done no violence, neither was any deceit in his
10 Yet it pleased the LORD to bruise him; he hath put him to grief:
when thou shalt make his soul an offering for sin, he shall see his
seed, he shall prolong his days, and the pleasure of the LORD shall
prosper in his hand.
11 He shall see of the travail of his soul, and shall be satisfied:
by his knowledge shall my righteous servant justify many; for he shall
bear their iniquities.
12 Therefore will I divide him a portion with the great, and he
shall divide the spoil with the strong; because he hath poured out his
soul unto death: and he was numbered with the transgressors; and he
bare the sin of many, and made intercession for the transgressors.
The ideology around the Messiah has a central position in Christian theology, even if there are dramatic differences from present Jewish ideas of Messiah: In Christianity, Messiah has already returned and his new kingdom has started. Together with this, a new interpretation of the religion has started, as it is described in the New Testament.
The Messiah of Christianity is Jesus. The term "messiah" has been translated into Greek with "christos", and Jesus is therefore called Jesus Christ in Christianity, which would be similar to Jesus the Messiah.
There are several references to the messiahship of Jesus in the Gospels. His qualities are revealed already at his conception (Matthew 1), at his birth (Luke 2) and during his baptism (Mark 1). Demons (Luke 4) and Peter as well have Jesus confirmed this (Matthew 16). And according to the Gospels, Jesus provoked the Jews to have him crucified simply by admitting to be Messiah (Mark 14).
THE GOSPEL ACCORDING TO SAINT MATTHEW, Chapter 1
20But while he thought on these things, behold, the angel of the
LORD appeared unto him in a dream, saying, Joseph, thou son of David,
fear not to take unto thee Mary thy wife: for that which is conceived
in her is of the Holy Ghost.
21And she shall bring forth a son, and thou shalt call his name
JESUS: for he shall save his people from their sins.
22Now all this was done, that it might be fulfilled which was
spoken of the Lord by the prophet, saying, 23Behold, a virgin shall
be with child, and shall bring forth a son, and they shall call his
name Emmanuel, which being interpreted is, God with us.
Peter answered and said, Thou art the Christ, the Son of the living God.
17And Jesus answered and said unto him, Blessed art thou, Simon
Barjona: for flesh and blood hath not revealed it unto thee, but my
Father which is in heaven.
THE GOSPEL ACCORDING TO SAINT LUKE, Chapter 2
9And, lo, the angel of the Lord came upon them, and the glory of
the Lord shone round about them: and they were sore afraid.
10And the angel said unto them, Fear not: for, behold, I bring you
good tidings of great joy, which shall be to all people.
11For unto you is born this day in the city of David a Saviour,
which is Christ the Lord.
12And this shall be a sign unto you; you shall find the babe wrapped
in swaddling clothes, lying in a manger.
13And suddenly there was with the angel a multitude of the heavenly
host praising God, and saying, 14Glory to God in the highest, and
on earth peace, good will toward men.
41And devils also came out of many, crying out, and saying, Thou
art Christ the Son of God. And he rebuking them suffered them not to
speak: for they knew that he was Christ.
THE GOSPEL ACCORDING TO SAINT MARK, Chapter 1
11And there came a voice from heaven, saying, Thou art my beloved Son, in whom I am well pleased.
61But he held his peace, and answered nothing. Again the
high priest asked him, and said unto him, Art thou the Christ, the Son
of the Blessed? 62And Jesus said, I am: and you shall see the Son
of man sitting on the right hand of power, and coming in the clouds of
63Then the high priest rent his clothes, and saith, What need we
any further witnesses? 64you have heard the blasphemy: what think
ye? And they all condemned him to be guilty of death.
The ideology of the Mahdi in Islam has many similarities with the Jewish/Christian Messiah. The ideology is central in Shi'i Islam but has a certain presence in Sunni Islam as well.
While Christian and Jewish thinkers would say that this ideology is strongly influenced by their two religions, Muslim thinkers would say that Mahdi represent the true form of saviour figure, and that Messiah in Judaism and Christ in Christianity represent deviations from the original doctrines.
Mahdi is a character that belongs to the last period of mankind, and his purpose is to restore the faith, and bring Islam back to its pure origins and provide for the belivers a society where they can perform their religious duties in a correct manner.
The Mahdi is not mentioned in the Koran, but belongs to theological developments starting from the 9th/10th century BCE.