(As I understand it.). Jihad against the world. Holy war against everyone not muslim.
Here’s a snippet.
The Black Standard is one of the flags flown by Muhammad in Muslim tradition. It was historically used by Abu Muslim in his uprising leading to the Abbasid Revolution in 747 and is also associated with the Abbasid Caliphate. It is also a symbol and is associated with Islamic eschatology (heralding the advent of the Mahdi).[Note 1] The Black Banner, which is different from the flag used by ISIL. Scholars have interpreted ISIL's use of a similar black flag in attempts to their claim to re-establishing a Caliphate.
The general consensus of Muslim scholars agree there would be tremendous and distinctive signs before the world ends. Among which would be an era of trials and tribulations, a time of immorality followed by mighty wars, worldwide unnatural phenomena and the return of justice to the world. Defining figures are also prophesied such as the Mahdi, and the Second Coming of Isa (known as Jesus in Christianity) who bring about a heavenly victory against Dajjal (Antichrist according to Christianity) ending with the release of Yajuj and Majuj (Gog and Magog) to the world.[4] Once all the events are completed, the universe shall be destroyed and every human being would be resurrected to be held accountable for their deeds.
The Mahdi (Arabic: ٱلْمَهْدِيّ, romanized: al-mahdīy), i.e. the "Rightly Guided One", is a messianic figure descended from Muhammad through Ali, who (with the help of Jesus) will defeat the Dajjal, reestablish Islamic law, rid the world of bid'a (religious innovation), and fill it with justice;
(Sunni and Shia disagree on details such as whether he is currently alive, will kill the Dajjal himself, what he looks like, his exact ancestry, etc.)
Jesus (Arabic: عِيسَى ٱبْنُ مَرْيَمَ, romanized: ʿĪsā ibn Maryam, lit. 'Isa, son of Maryam') will make a second coming, descending to earth, but unlike in Christianity it will be to assist the Mahdi by killing the dajjal, "break[ing] the cross, kill[ing] the pigs, and abolish[ing] the Jizya tax",[31][32] i.e. put an end to Christians misconceptions about his being the Son of God and there being no need to follow dietary laws.
Jesus and the Mahdi will then rule the earth in perfect justice for a time before Judgement Day. (Shia believe it is the Mahdi who will kill the dajjal; others believe "the Mahdi" is not a distinct person but just the title given to Jesus.)
What does it mean I'm unfamiliar with it
(As I understand it.). Jihad against the world. Holy war against everyone not muslim.
Here’s a snippet.
The Black Standard is one of the flags flown by Muhammad in Muslim tradition. It was historically used by Abu Muslim in his uprising leading to the Abbasid Revolution in 747 and is also associated with the Abbasid Caliphate. It is also a symbol and is associated with Islamic eschatology (heralding the advent of the Mahdi).[Note 1] The Black Banner, which is different from the flag used by ISIL. Scholars have interpreted ISIL's use of a similar black flag in attempts to their claim to re-establishing a Caliphate.
The general consensus of Muslim scholars agree there would be tremendous and distinctive signs before the world ends. Among which would be an era of trials and tribulations, a time of immorality followed by mighty wars, worldwide unnatural phenomena and the return of justice to the world. Defining figures are also prophesied such as the Mahdi, and the Second Coming of Isa (known as Jesus in Christianity) who bring about a heavenly victory against Dajjal (Antichrist according to Christianity) ending with the release of Yajuj and Majuj (Gog and Magog) to the world.[4] Once all the events are completed, the universe shall be destroyed and every human being would be resurrected to be held accountable for their deeds.
The Mahdi (Arabic: ٱلْمَهْدِيّ, romanized: al-mahdīy), i.e. the "Rightly Guided One", is a messianic figure descended from Muhammad through Ali, who (with the help of Jesus) will defeat the Dajjal, reestablish Islamic law, rid the world of bid'a (religious innovation), and fill it with justice;
(Sunni and Shia disagree on details such as whether he is currently alive, will kill the Dajjal himself, what he looks like, his exact ancestry, etc.)
Jesus (Arabic: عِيسَى ٱبْنُ مَرْيَمَ, romanized: ʿĪsā ibn Maryam, lit. 'Isa, son of Maryam') will make a second coming, descending to earth, but unlike in Christianity it will be to assist the Mahdi by killing the dajjal, "break[ing] the cross, kill[ing] the pigs, and abolish[ing] the Jizya tax",[31][32] i.e. put an end to Christians misconceptions about his being the Son of God and there being no need to follow dietary laws.
Jesus and the Mahdi will then rule the earth in perfect justice for a time before Judgement Day. (Shia believe it is the Mahdi who will kill the dajjal; others believe "the Mahdi" is not a distinct person but just the title given to Jesus.)