“In the early 21st century, following the failure of the Arab Spring and defeat of the self-proclaimed “Islamic State”, there has seen “a broad mainstream embrace of a collective Muslim identity” by young Muslims and the appeal of a caliphate as a “idealized future Muslim state” has grown ever stronger.”
~ Wikipedia
If a global, single Islamic caliphate or state emerges, then, truly, Islam will be revealed as it truly is, not a religion, but a civil, political, government, state authority or power, and, if or when that happens, Islam could be banned from many nations on constitutional grounds, because it sponsors terrorism and denies basic human rights,, and, as a hostile political ideology, support of it could be a treasonable offence.
Claiming to be a religion and not a political ideology offers it cover to pursue an Islamic state under the cover of freedom of religion.
Ian Vincent 
April 26, 2019 at 4:56 am
The Imams (scholars of the four schools of thought)- may Allah have mercy on them- agree that the Caliphate is an obligation, and that the Muslims must appoint a leader who would implement the injunctions of the religion, and give the oppressed justice against the oppressors. It is forbidden for Muslims to have two leaders in the world whether in agreement or discord.
Shia scholars have expressed similar opinions.[92][93][94][95] However, the Shia school of thought states that the leader must not be appointed by the Islamic ummah, but must be appointed by God.
Al-Qurtubi said that the caliph is the “pillar upon which other pillars rest”, and said of the Quranic verse, “Indeed, man is made upon this earth a Caliph”:[96][97]
This Ayah is a source in the selection of an Imaam, and a Khaleef, he is listened to and he is obeyed, for the word is united through him, and the Ahkam (laws) of the Caliph are implemented through him, and there is no difference regarding the obligation of that between the Ummah …
An-Nawawi said:[98]
(The scholars) consented that it is an obligation upon the Muslims to select a Khalif
~ Wikipedia