Christian Nationalism is a heretical - and increasingly dangerous - ideology - that is becoming prevalent in the US and in European nations. It begins with the idea that our country - one that believed to be primarily white and Christian - is better than others, that God favors us more than them, and that policy should be dictated by that.
That's a huge oversimplification! Here are a couple of videos to give you more background. The first is a statement against Christian Nationalism from our presiding Bishop, Elizabeth Eaton.
The second is of Amanda Tyler, head of the organization, Christians Against Christian Nationalism, speaking in Congress about what it is and what the dangers are.