Right, so we have the issue of popular sentiment vs behavior of the rulers. I think when people (especially Western ones) say things like "secularism can never work in Muslim countries," they're referring to the former. Like this deep religiosity is such a part of the culture, that secularism is rejected outright.
But the truth is that the population HAS embraced secularism, and it could be argued that they could even embrace it today. But their rulers and outside forces are the ones that stoke the fires of fundamentalism
But that's not always the case. You're missing the fact that in the in 20th century the rulers did the opposite, they embraced secular ideologies and in many countries the population went with them. But those projects failed which undermined those ideologies and the populations turned towards Islamism, especially as those secular elites became an ineffectual and corrupt ruling class.
(It should be noted that secularism doesn't = atheism. Kurdish areas are rightfully seen as models of political organization in the area by many Western leftists because of their secularism, BUT they're almost 95%+ Muslim themselves. They just don't infuse their religious beliefs into state affairs.)
Yeah sure I wouldn't conflate the two. Secularism can mean different things; French style secularism which means confining religion to the realm of private affairs or American style secularism which means the state endorses no religion but society may or may not be publicly religious. Secularism in the Muslim world is more often influenced by French style secularism(unsurprisingly given the history of French colonialism in the region) though at times the secular elites have had to make certain small concessions to the conservatism of their populace such as writing into the constitution that Islam is the religion of the state(while making sure that this has few to no practical implications for day to day affairs).
Obviously Islamist governments don't have a monopoly on authoritarianism, but they almost invariably enhance it when they're in power or when they have influence.
In many ways Erdogan is less repressive than the Kemalist military elite he swept away but for the reasons I mentioned earlier(ambivalent relations with the West, encourages religious norms like hijab and mustaches) he has a worse reputation in the West. Again Westerners don't really care about human rights in the Muslim world as much as they care about the optics; they don't care if its a police state if the women wear skirts instead of hijabs.
In fact he's become more repressive as he's returned to the more Turkish nationalist character of the Kemalist establishment while he was actually a democratizing force in the early reforms years when, leaning on Islamic identity politics, he reduced the role of the military, sought to reconcile with the Kurds, and relaxed restrictions on public displays of religion.
So your article actually contradicts your point here. The same holds true for Egypt; the Muslim Brotherhood government under Morsi is far, far less repressive than Sisi's anti-Islamist government.
It's a complicated picture but the main idea is that secularism could/is widely embraced by the Turkish people, but Erdogan is pushing a particular form of Islamism:
This article explains it nicely-
https://www.hoover.org/research/erdogan-nationalist-vs-erdogan-islamist
That article makes the point that I've made elsewhere, that Erdogan represents the return of Turkish nationalist authoritarianism more than genuine Islamism. Erdogan is probably closer in values to Macron in his values than an austere religious man like Mohamad Morsi.
How did Pan-Arab Nationalism fail here? If anything a united Arab coalition working synchronously with each other was a better alternative than individual Nations/Kingdoms taking on Israel one by one.
Because the Arab nationalists failed in their mission to defeat the Zionists and develop the country. Not sure how much more clear I can be than that.
Ok so Islamism provided social, political and economic stability during times of flux when foreign secularism/nationalism was linked to economic turmoil. In times of turmoil and depression (Post Enlightenment) Europeans did not go back to the Holy Roman Empire and Feudalism, its time was over. They instead moved to modern forms of governance like Communism, Fascism, Constitutional Monarchies, Constitutional Republics. This goes back to Islam being a much more robust social, economic and political system than any other religion today and why it's so easy for muslim societies to "fall back" on what they once knew.
Islamism is a modern movement though. Sure it draws from the deep Islamic tradition but its forms and structures are wholly modern and most traditional Islamic institutions(Sufi lodges,
waqf, sharia courts, guilds) have been swept away in the vast majority of Islamic countries with only a few exceptions(Sufi brotherhoods remain popular in Senegal where ~95% of the population is part of one).
The modern Islamist movement is composed of civil society organizations like charities, professional organizations, unions, student associations and so on and so on.