There is quite a bit of scientific evidence that points in the direction, that suggests that homogeneous societies are beneficial.

More diverse neighborhoods have lower social cohesion.

A 10% increase in diversity doubles the chance of psychotic episodes.

Diversity reduces voter registration, political efficacy, charity, and number of friendships.

Ethnic diversity reduces happiness and quality of life.

Diversity reduces trust, civic participation, and civic health.

Diversity primarily hurts the dominant ethnic group.

Ethnic diversity within 80 meters of a person reduces social trust.

Ethnocentrism is rational, biological, and genetic in origin.

Ethnic diversity harms health for hispanics and blacks.

Babies demostrate ethnocentrism before exposure to non-whites.

Ethnocentrism is universal and likely evolved in origin.

Races are extended families. Ethnocentrism is genetically rational.

It is evolutionary rational to be friends with someone genetically similar to you.

Racism and nationalism are rational and evolutionary advantageous strategies.

Ethnically homogeneous neighborhoods are beneficial for health.

Homogeneous polities have less crime, less civil war, and more altruism.

States with little diversity have more democracy, less corruption, and less inequality.

I chose National Socialism since it is the ideology that best suits my views, regardless of whatever controversy it may have attached to it, it's still the most accurate name for my views. Even if I choose a similar but different ideology, I'd likely still get called a Nazi and be controversial, especially due to the ethnocentric aspect.

The Third Reich was a very specific situation with a very specific set of people interpreting the ideology, everything they did is not necessarily a vital part of the ideology itself, but rather a part of the specific interpretation and circumstances.