Nobody is saying that being a human is illegal, or that they are innately illegal.

The headline:

Illegal foreigners

But in case you’re honestly trying to learn:

Use an adjective to describe a person. Don’t use a noun to label to them.

Christian’s are the exception because they “took it back” like over a thousand years ago when they became the majority, it’s perfectly fine for them to prefer that. But it doesn’t effect any other group.

And it’s not just religions, literally every group in every conversation;

Use adjectives.

Not nouns.