It's possible you interpreted this differently than it was intended as a non-native speaker. In case that's true, I'll note that rather than referring to people who are "religious", "white", or "nationalist", the OP was likely referring to people who are "religious" and "white nationalist". White nationalists are people who want to establish a white ethnostate, and typically this label is adopted by white supremacists who want to leave behind the "white supremacist" label but maintain the same ideology.