Nationalism 2025 is just another top-down (Leftist) ideology

Real bottom-up nationalism was a phenomenon of the late 19th and early 20th century - it was, indeed, the first attempt by developing nations to do without religion as the basis of social cohesion (specifically, it was the first post-Christianity ideology.

Instead of a common religion, the basis for social cohesion was intended to be racial and national identity - "blood and soil". 

This early nationalism sometimes worked as a primary motivator, perhaps because it necessarily included a residue of common national religion (e.g. in Ireland, or Spain - where, for a while, nationalists ruled in collaboration with the Roman Catholic Church) - but this strength was always brief, and faded after a generation or so. 

Since then (and this includes the post-empire forms); nationalism has been, like all other forms of mainstream politics, essentially a top-down, ruling-class-driven ideology. 

Later nationalism was (and is) a "local elites" project. 

That is; a matter of the local clerical and managerial class (often journalists, school teachers and clerks) trying to propagandize the masses to support their plans of fragmentation of a larger political unit, into smaller national groupings. 

This fragmentation brought new career and other opportunities for the local elites - who had previously been kept-out of power by the larger-unit's leadership class. 

But the bottom line is that such nationalism is just-another variant of Leftism: i.e. it is a type of secular materialism, with utilitarian values rooted in this-worldly hedonism (i.e. the claim to optimize human gratification - in this instance of indigenous members of the nation). 

Nationalism nowadays shares the arbitrariness and incoherence of other Leftisms: it entails vast efforts of propaganda to be disseminated by media and education, and enforced by laws and the state bureaucracy. 

It survives by pandering to the local elites, whose careers and status depend on sustaining the nationist fictions - however feeble.  

What is more, in the past several decades nationalism has failed everywhere from Ireland to Iceland to sustain itself. 

Indeed, even ideologically-"nationalist" leaders have in practice and overwhelmingly willingly and enthusiastically embraced the most destructive aspects of globalism, from self-subjection to multi-national groupings and agencies (EU, UN-WHO etc), assimilation into international finance and trade; and enforced native population subordination-to and replacement-by the necessarily destructive phenomenon of mass immigration. 

Self-styled nationalism in 2025, such as that in Scotland, Australia, New Zealand; is merely a film of window-dressing applied to conceal some of the most globalist servile and native-population self-destructive even in our corrupted world!

Nationalism as of here-and-now is therefore a false and delusional hope - futile at best, but most likely just-another agent for the agendas of international totalitarianism and/or societal chaos leading towards WWIII.