I have no position.
But I have a very good idea on what might happened.
As there has been so many cases happened throughout the entire history.
A conflict will occur between natives vs immigrant.
Ultranationalism will gain more support as the natives felt threatened.
In reaction Ultra-religionism will also gain more support among the immigrant as they're also feel threatened and their social identity / culture is in danger of being assimilated into the natives culture. Ultra-religionism is after all preach about the importance of "Religion Purity, free from paganistic / foreign influence" vis-a-vis Ultra nationalist ideology of "Nation purity, free from foreign influence".
And when two opposites fanatical groups met, we can guess what's the results will be.
Peaceful coexistence can happened if only the two groups tolerate the others. Which requires both parties to abandon their "purist" ideology. The tradition of the natives will be "tainted" with the tradition of the foreigners / immigrant, and the tradition of the immigrant / foreigners will be "tainted" with the tradition of the natives.
Statistical occurrence of the above scenario, without any conflict, is very small, unless both group intermarried with each others giving birth to a brand new generation of "hybrid / mixes" which shall be "tainted" with both tradition / religion / culture.