I think it culture should i some way be factored in, but religion still held its baleful influence on the world. So although, two people might might be close culturally they could still be separated by the chasm of religion.
You mention Ireland, well that country has a sad history of conflict in which religion has played a major role. Again, I think that as a non British person you might be hard pushed to clearly spot the cultural differences between Ireland and Britain,: they speak English, the place looks British in many ways (buildings, streets, institutions, driving on the left, etc...). But it isn't British and they still wanted the Brits out.
Quebec has never changed its language nor have the people changed their religious affiliations, yet after the British take over there was relatively little (if any) dissent in the province. In fact it is only recently with the wave of nationalistic demands of the post ww2 that political agitation has come in earnest.
The difference is that in Ireland Britain interfered drastically with society, whereas in Quebec they left it alone.