The reason why some hmong back in the 1950’s fell for christianity is multi faceted.
1) the christians/catholics were cunning and disingenuous. They mostly only went to remote rural areas where the hmong had little to no education. Indeed, start with the weakest link. These hmong probably only knew as much about the world as far as they could walk, and that was to the farm field and around the village. That was their circle of knowledge. Obviously theres a huge gap of power dynamics here between the french/white priest/missionary and that of the hmong villager. The french priest was well travelled; came nearly half way around the world. And so like any person who is more educated, more knowledgable, more experienced, will be able to counter any objections coming from the lesser educated one... when the hmong ran out of ideas, and that was quick, they thought and rationalized, wow, jehova must be real since these farang fabkis know so much. Jehova/yesxus = vammeej! Yah and they even have books, of which hmong so covet (because according to stories/lores, the chinese burnt the hmong writing system and hmong have been desiring such a thing for generations).