I read an interesting post on reddit not so long ago, it was talking about how religion and nationalism are not compatible, which is especially true about secular countries which most European countries are.
Both nationalism and religion require that you're devoted and loyal to their respective boundaries. But too often we forget that if you're a nationalist you will notice a pattern and eventually it becomes clear, these Judaism Religions didn't make things better, you look at the crusade which fucked up quite a lot of pagan countries which made the Muslim expansion even stronger. But I will give you guys this Europe back then was very much defragmented so I suppose most peoples religious beliefs was a much stronger idea to follow then the idea of nationhood. All they cared for back then was food on the table and being good enough to get to heaven. That is all well and dandy, cultures and national ideas and the principles most nations have revolved around a Christian way of life, but we can see that this has backfired quite a bit. We can blame the left or fake conservative all we want, but it was a religion which paved the way to this, not nations. A leader can only do so much without his people.
Back to the point religion nowadays shouldn't be left out, especially not Christianity, it should stay there until we can get rid of the Muhammedans.
Also, do not forget to preserve your culture, your nation and the way of life cause darn it, it's important!