Here's another religious sect which was a part of the competition for South Vietnam which opposed the Cao Dai.
The video I linked says the Cao Dai sided with the French but for a while they were opposed to Catholicism and from what I've researched it seems that a lot of eventually people had to choose between the Viet Minh or French, even if they were not supportive of either but did not like the non-religious attitude of the communists. There was even a Japanese element in the conflict.
https://en.wikipedia.org/wiki/H%C3%B2a_H%E1%BA%A3o
The video I linked says the Cao Dai sided with the French but for a while they were opposed to Catholicism and from what I've researched it seems that a lot of eventually people had to choose between the Viet Minh or French, even if they were not supportive of either but did not like the non-religious attitude of the communists. There was even a Japanese element in the conflict.
https://en.wikipedia.org/wiki/H%C3%B2a_H%E1%BA%A3o