Some Secularised 'Muslims' attempt to argue the Islamic idea of the Caliphate even be rejected by Muslims and that it isn't obligatory to establish! They, along with their Islamophobic Westerner allies even attempt to link belief in the Caliphate to terrorism!
It's strange for a number of reasons.
First: The Islamic belief in the necessity of a Caliphate is Inextricable from Islamic Sources
Belief in the Islamic Concept of a Caliphate is inextricable from Islam. The word Khilafah comes from the Qur'an and the term 'Caliph' was used of the leadership of Prophet David (a.s.) over the tribes of Israel in Canaan. It is also used in the Qur'an dealing with Muslims who do righteousness being granted Khilafah upon the earth.
'[We said], "O David, indeed We have made you a Caliph upon the earth, so judge between the people in truth and do not follow [your own] desire, as it will lead you astray from the way of Allah ." Indeed, those who go astray from the way of Allah will have a severe punishment for having forgotten the Day of Account' [Qur'an 38:26]
Secondly, the word also comes from the hadith (traditions) of the Prophet Muhammed (saw) with very explicit commands regarding pledging allegiance to a Caliph, ensuring rulers rule by Islam and ensuring there is only one ruler over Muslims - to fulfil the Qur'anic requirement for Unity (in order to preserve Muslim strength and prevent fitna).
The Prophet Muhammed (saw) is narrated to have said: "There will be no prophet after me, but there will be Caliphs who will increase in number." The people asked, "O Allah's Apostle! What do you order us (to do)?" He said, "Obey the one who will be given the pledge of allegiance first. Fulfil their (i.e. the Caliphs) rights, for Allah will ask them about (any shortcoming) in ruling those Allah has put under their guardianship."
[Sahih Al-Bukhari. Hadith 4.661,Narrated by Abu Huraira]
The Prophet Muhammed (saw) is narrated to have said: "Whoever dies and did not make an oath of allegiance (to the Muslim leader) has died a death of jaahiliyyah." (Narrated by Muslim, 1851).
The Prophet Muhammed (saw) is narrated to have said "Whoever gives his oath of allegiance to a leader and gives him his hand and his heart, let him obey him as much as he can. If another one comes and disputes with him (for leadership), kill the second one." (Narrated by Muslim, 1844)
The Prophet Muhammed (saw) is narrated to have said: "If allegiance is given to two khaleefahs, then kill the second of them." (Narrated by Muslim, 1853).
The Prophet Muhammed (saw) is narrated to have said: "Even if a slave was appointed over you who leads you with the Book of Allah then hear and obey." [reported by Sahih Muslim]
However, even if the obligation of Caliphate wasn't explicitly mentioned by the Prophet Muhammed (saw) would still be a necessity deduced simply the amalgamation the obligation upon to Muslims to A) establish the justice of Islam collectively in laws and organised duties and B) Unity. In fact, the only difference of opinion Islamic scholars had (as Ibn Khaldun discusses in his muqadimmah) is whether the obligation of Caliphate is primarily deduced from Prophet's Muhammed's explicit commands about it, or by rational necessity of fulfilling all of Islam's requirements (Ibn Khaldun cited the former).
All schools of thought in Islamic fiqh and Aqeedah are in general agreement about the Caliphate. The Shia block only disagreeing with the Sunni bloc on how far the Caliph's powers go and who should be the Caliph (Shias believe the Caliph should also have power to be obeyed on matters outside of politics and that only a designated member of the Prophet's family can fulfil that role).
Second: No credible difference of opinion on Caliphate in 1,400 years
When looking through 1,400 years of Islamic scholarship, the challenge isn't to find scholars that advocated the necessity of a Caliphate, but to find those who didn't! After spending much research trying to find just one scholar that didn't believe Caliphate was an obligation, I only found a small faction of the Khawarij (ironically appropriate) who came from Najd, believed that Muslims didn't need a Caliphate, as they believed that ALL Muslims can implement the hudood and other laws collectively (i.e. socio-Anarchism).
The Najdi Khawarij branch was famous for arguing with CALIPH Ali (ra) that only God should be the political ruler, not Ali (ra). To which Ali (ra) refuted them, by challenging them to put the Qur'an on a throne and make it rule [In a debate between Ali (ra) and Khawarij, would you really want to take the Khawarij's side?!).
The only other scholar was the Mutazilite, Abu Bakr al Assam who believed that the Caliphate was only not an obligation IF it was possible for the Muslim community to implement ALL Islamic laws without ANY GOVERNMENT. However, it they couldn't THEN the Caliphate was obligatory. The majority of Mutazilites, however, all believed that Caliphate was an obligation - and three Caliphs were even Mutazilites!
It should be noted, that even in these cases, no Muslim ever argued that another form of government was permitted. Especially not one that denied God's law!
Even scholars that many Secularised Muslims (ignorantly) look up to, condemned other forms of government, Ibn Sina, Ibn Rushd all discussed other forms of government and (like their Greek muses) condemned Democracy as one of the worst forms of government.
Ibn Farabi in his Kitab al Siyasah al-Madaniyyah (The Book of the Political Regime) even, amazingly, predicted that if Democracy were to exist, it would be dominated by the rich who could buy influence.
Now even if a Seculariser were to bring up the Mutazilite al Assam and the Najdi Khawarij has 'valid difference of opinion'. It would not follow that they could criticise those who follow the (overwhelmingly) majority-to-the-point-of-virtual-consensus opinion. For if they call on Muslims to 'respect their difference of opinion', then they too CANNOT tell Muslims it is against Islam to publicly campaign (politically peacefully) for the re-establishment of the Caliphate, for Muslims have an equal right to follow the (vast majority) opinion too.
However what you'll find, is that Secularisers can be every bit as intolerant as those they misrepresent being intolerant of their ideas. When Muslims criticise them, they hold up their hands and cry 'difference of opinion!', but when Muslims reject Secularism or advocate an Islamic ideal that is contrary to Secularism, Secularisers will decry it as 'extremism!', denounce all those who believe in it, ask the West to clamp down on those opinions and call for the destruction of these ideas from all societies. Secularisers demand Secularism and won't tolerate anything less.
Third: The Argument that Belief in a Caliphate Causes Violence can apply to all forms of Political Government (and more so to Secular ones)
Many Western politicians and strategists, since even before World War 1, looked at the concept of a Caliphate as a big obstacle for their imperial designs in the Muslims world (i.e. cheap resource extraction, strategic military projection against other powers). Western politicians, like Sir Mark Sykes (the man behind the disastrous Sykes Picot agreement) were open  about the necessity of dismantling and destroying the Caliphate under the Ottoman administration and his successors have been vehemently opposed to its establishment ever since. Similarly, many people from Muslim backgrounds who embraced Secularism, view the hope in the Muslim world for the revival of a Islamic Caliphate, as an obstacle to the introduction and preservation of the artificial colonial construct that gave 'birth' to them, of the Secular Nation-State.
However, Western politicians and 'Muslim' Secularisers have found it difficult to persuade the Muslim world that unity (and its accompanying strength) under the justice and laws of God, is something Muslims shouldn't want. So instead they've had to adapt their polemic and attempt to claim that the Caliphate will produce nothing but harm to Muslims.
Secularisers know deep down that belief in Caliphate produces no more violence than someone believing in the nation-state of United State of America. However, Secularisers need to use a gimmick in order to argue against it, because the Islamic Concept of Caliphate (and Islamic law) is one of the biggest obstacles to the wholesale Secularisation of the Muslim world. Of course, this is reflected in the strange and self-contradictory arguments they use.
For example, Secularisers argue that the belief in the Caliphate produces Terrorism and then point to a supposed 'history' of terrorism amongst Muslims starting with the 'Wahabbis'. It seems to have been lost on them, that the Saudi revolt wasn't done in the name of a Caliphate, but it actually fought against the Ottoman Caliphate! After the destruction of the Ottoman Caliphate, the Saudis were rewarded by the British for their collaboration with control over the lands of Arabia (whose boundaries were determined by Sir Percy Cox). Saudi Arabia isn't the cause of terrorism, but actually a post-colonial nation-state, whose job since its inception is to maintain the status quo and ensure the oil flows to the West (including lavish welcomes for American presidents like Trump). This becomes clear when you ask yourselves this: if the 'ideology' of Saudi Arabia promotes Caliphate, why haven't the Saudi's declared themselves as a Caliphate? The answer is, Saudi Arabia was built on the ruins of the (Ottoman) Caliphate and are not seeking any return of it - quite the opposite in fact.
Secularisers then point to Terror attacks in the West, or in the Middle East, citing the belief in Caliphate as somehow the cause. Yet again, this is disproved by the claimed motivations of the terrorists themselves , who invariably cite Western foreign policy grievances. If simply belief in a Caliphate causes Muslims to spontaneously attack any nearby non-Muslims, why haven't these Secularisers explained why no Muslim perpetrated terror attacks happen in South America (strong Muslim populations there, like Suriname, which has a Muslim population 14%), or South Africa (Muslim population comparable to UK proportion), Switzerland (Western Country) or Ireland (another Western country)?
The answer, I suspect, is to be found in what all these countries foreign/domestic policies all have in common with each other.
Of course, the arguments of Secularisers full of hypocrisy in this regard. Just yesterday, during a UK election debate, an audience with a strong demographic of Conservative Party supporters lambasted Labour party leader Jeremy Corbyn for refusing to confirm whether he'd ever fire the UK's nuclear missiles as an enemy country's civilian population, murdering millions . The Conservative supporters wanted Corbyn to agree with them that he would! Indeed Theresa May , the acting Prime Minister of the UK confirmed in parliament that she would fire Nuclear weapons even if hundreds of thousands people would die in the process - all presumably in the name of the national interest, or to put it simply, the British Nation State.
The Hypocrisy of Secularisers telling Muslims that belief in Caliphate makes people justify killing thousands of civilians, while belief in nation state - is socially accepted in the West to justify killing millions in 'the name of the nation'. Of course, Secularisers would argue, the Conservative party supporters only justify killing enemy civilians if the enemy kill ours'. To which I respond "How is that ANY DIFFERENT to terrorists who attempt to justify killing enemy civilians in retaliation for their dead civilians?!"
This logic is warped and disgusting and very much part of Western political philosophy. The so called 'Muslim' terrorists don't kill people because they believe they're imitating the Prophet Muhammed (saw), they do so because they are imitating the West - which is something Osama Bin Laden openly admitted. In light of this, we should all ask Secularisers who want Muslims to imitate the West, how imitating the West is going to stop terrorism - when it is an idea the Terrorists imitated from Western military history in the first place?!
The truth that Secularisers don't want people to realise, is that nationalism has caused more wars and terrorism in the last 200 years than anything else. for most of the 20th Century, Terrorism was caused mostly by nationalist groups (many of them supported by the CIA in South America), where in the name of 'Freedom' and 'The Nation' people were brutally murdered, raped and even beheaded in the thousands. In fact, the (in)famous Secular revolution of the Enlightenment, the French Revolution, in the name of 'Liberte (Freedom), Egalite (Equality) and Fraternite (Brotherhood of Citizens), beheaded thousands of French people, including, Catholic clergymen (priests and nuns). They beheaded so many people, they even invented a machine to do it efficiently, called La Guillotine. They beheaded so many people, ISIS's horrific record pales by comparison to this Secular movement.
Indeed, the biggest killer of Muslims in the Muslim world is the War on Terror by America and its allies, which has caused a death toll that dwarfs the death toll by all other terror groups in the region combined. Would the Secularisers be willing to devote the same amount of energy to defeating the America and the ideology behind its violence now (which is Secular Liberalism)? Doubt it - a child does not easily reject the parents that gave birth to them.
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