I'm not sure if they would have founded it again were it not for qyrvaggism, Riombara or not. They might have been content with atheist, but as with most people, they would not have tolerated any faith from an unfriendly realm showing up. Likely, not any faith at all except a select few trusted ones from friendly people and places.
Which makes sense, to grow a religion still needs to work and win over the local nobility, just if we reduce the amount of pointless religions (not necessarily small ones mind you) there could be greater scope in which to operate in this way.
