How to make my vassals Christian?

[Das Boot]

I'm playing as the Otomo, and I conquered half of Japan and converted it to Christianity. I have provoked Christian revolts in the lands outside my realm to create a buffer between me and the remaining 3 clans who formed a power-block against me. I'm considering creating vassals from these rebels, but I want to make sure the vassals are Christian too.

Is it enough to convert the rebel settlements to Christianity prior to invading and releasing them as vassals? Or is it out of my control?

[BastardSword]

Can't. Clans have to choose to convert on their own to a religion, and you can't choose for them. The only clan that starts as Christian is Otomo, all the others are by default Buddhist.

Sending a missionary in to convert the population of their provinces won't do anything either. A province's religious makeup is separate from the clan's chosen religion. By converting their people all you'll do is cause unrest because the vassal clan will be Buddhist but the province's people will be Christian, and eventually a rebellion will happen.

By converting the provinces MAYBE the vassal AI would choose to convert to Christianity to avoid unrest, but I really doubt it.

[easytarget]

Put up enough churches in the vicinity of the province and it'll likely flip whether they like it or not. In any case as a vassal the morale ding either way doesn't matter because it's the vassals problem not yours.