If you want a good primer to Ba'athism - this video helped me (CW: channel is patsoc vibes, despite renouncing Caleb Maupin, so take it with a grain of salt)
beyond that I’ve heard a lot of claims about it ranging from accusations of it basically being Arab Fascism
Oh that reminds me
as you would know, pan-Arab nationalism is surprisingly but understandably pro-secular, meaning due to lack of religious influence on the Arab state, anyone who is Shia or Sunni Muslim, Christian, or any derivative could socially mobilize, unlike a pan-Islamic movement.
The thing I find wrong with once-existing Ba'athism is it inexplicably leads to minority rule (Alawite-dominated party over Sunni majority Syria or Sunni-dominated party over Shia majority Iraq)
This proved to be the contradiction that undermined these states, besides, ofc, the external factor of U.S imperialism helping cause the destruction of these states through its relentless sanctions and war against them.
