Ian created the well-thought Unionist ideology in the Unity TL. Can anyone else think of some sort of ideology that can captivate nations and nation-blocs, leading to world war? The closest ones I’ve found were also in his TLs, such as the established form of anarchism in his Atomic League TL and militarism in Draka 2.
Also, try to keep your ideology independent of a major religion. There have already been both Christian fascists and socialists; both Muslim socialists and nationalists exist. Such big faiths can support any variety of interpreters and religions. Also, while both National Socialism and the Japanese form of imperialism had ideas based on divinity and destiny (albeit wackier ones in the former, what with the combination of old-school racism, Odinism, and theosophy), they were pretty much different from mainline religions.
Also, try to keep your ideology independent of a major religion. There have already been both Christian fascists and socialists; both Muslim socialists and nationalists exist. Such big faiths can support any variety of interpreters and religions. Also, while both National Socialism and the Japanese form of imperialism had ideas based on divinity and destiny (albeit wackier ones in the former, what with the combination of old-school racism, Odinism, and theosophy), they were pretty much different from mainline religions.