Nationalism by its very definition is evil.
By design it holds the values of the country and ruling class/race/religion over individual rights and freedom. By design it marginalizes anyone who does not toe the party line, practice the party religion, or looks like the ruling party.
Nationalism is a synonym for fascism.
Definition:
Nationalism is an ideology that emphasizes loyalty, devotion, or allegiance to a nation or nation-state and holds that such obligations outweigh other individual or group interests.
Being a nationalist make you a boot licking sycophant.