I'm guessing by that, they mean "White Conservative Christian" (or someone who's willing to kowtow to what White conservative Christians want).
This topic gets extremely messy in the US.
US is a unique country in that it's a nation founded on a set of ideas rather than on some sort of ethnic or racial identity. For instance, one can "become an American", I could move to Japan, live there for 20 years, and nobody would consider me to be Japanese.
Incidental overlap obfuscates the situation. Some Americans see people from other countries coming here (with different sets of values), and fail to make the distinction between the values themselves vs. the immutable characteristics the people happen to have, and start to treat them interchangeably or attribute one to the other.
That's one aspect that other countries (even ones that are far more progressive than the US) have understood is that without some sort of common social fabric or shared set of ideas, it's going to be a rough road. Which is why a lot of the more progressive countries have far stricter immigration requirements than we have.
The rub is that those countries don't have any sort of claim to being a "melting pot" or a "place where anyone can come and live how they see fit"...that still is our "claim to fame" so to speak. If we implemented the type of strict immigration requirements that places like France, Finland, Sweden, or Japan have, a lot of people would be opposed to that and say "that goes against what this country was founded on!" (and they'd be right)
It's tough to balance the "open door"/"anyone can come and be a part of this" mentality with the type of social cohesion a nation needs in order to function with minimal conflict.