The Blood of Vol in Karrnath might do it, depending on how much you want to play up the Karrnathi crown's campaign against the Blood of Vol. You could have them being persecuted to the extent that they'd want to move.
Lastly, this isn't a religious group, but what about Cyreans? Cyreans who aren't content with New Cyre under Breland might want to try creating a new state elsewhere.
), so I'll explain in more detail.The idea is that the PCs are all leaders of this particular group of religious colonists, and they've moved to Xen'Drik to try to get away from corrupting influences of Khorvaire cultures. In the real world, the reason puritans ended up moving across the atlantic is because (while there were places where they were tolerated and respected in europe) their children would end up being raised in a different culture and thus gaining traits of this other culture, and the puritans didn't particularly like this. I want a group something like this - wannabe theocrats who couldn't stand heterodoxy and cultural drift and thus moved away.
EDIT: Whoops, ninja'd. I was wondering if their were any such groups in canon - I can probably make one up easily, but it'd be easier if I had something already.
The idea is that the PCs are all leaders of this particular group of religious colonists, and they've moved to Xen'Drik to try to get away from corrupting influences of Khorvaire cultures. In the real world, the reason puritans ended up moving across the atlantic is because (while there were places where they were tolerated and respected in europe) their children would end up being raised in a different culture and thus gaining traits of this other culture, and the puritans didn't particularly like this. I want a group something like this - wannabe theocrats who couldn't stand heterodoxy and cultural drift and thus moved away.
This is basically 1/3 of Q'barras population. They feelt that the five nations had betrayed the ideas of old Galifar, and they would not tollerate it any longer. So they moved. So you could just "move" the town of newthrone too Xen'drik.
Also, if you don't have it, Powers of Faerun would be mighty helpful in the colonialist aspect of the whole thing. It's marketed under Faerun but it's really useful for any setting.
No heterodoxy? Silver Flame all the way. Get your hands on Faiths of Eberron and you'll find all you need.
Hmm. I had glanced at it earlier and thought that none of them really fit, but looking over it again, the Knights Militant just might. Is there any more information on the Knights Militant other than on p. 69 of FoE?
There is a puritan sect of the Silver Flame, particularly in Aundair, but the Aundairan state doesn't really have a big problem with them, so they might not be interested in moving.
That's not quite "Puritan" in the sense the OP seems to mean. The Pure Flame sect in Aundair is more along the lines of the fanatical smiters that readers/writers tend to assume all Flame worshippers are.
I forgot to mention that the governments of Khorvaire, as well as the liturgical councils of the Sovereign Host, persecute those that mix worship of the Dark Six and the Sovereign Host, which might be further impetus for followers of the Restful Watch to emigrate.