Since the unwelcome arrival of Europeans, American history has been one long tug of war with white supremacy. Our best moments have been when we overcome white supremacy, and our worst moments have been when white supremacy has overcome us. Sadly, we are currently in a moment where it seems white supremacy is overcoming a large percentage of us, especially when it comes to our care (or lack thereof) for immigrants and refugees.
We can have disagreements on how to address challenges related to immigration and refugees, but the use of the term “illegals” as a way of classifying and thereby dehumanizing millions of persons is the kind of language that has led and continues to lead to concentration camps.
The term “illegal” used as an identifier for undocumented immigrants and refugees (as in “he or she is an illegal,” or “they are illegals,” or even simply saying “illegals” without an identifying pronoun), though currently more socially acceptable than using the n-word, is the functional equivalent to calling black people the n-word. Both identifiers are meant to dehumanize the other, thus justifying their treatment as less than human and thus not fully deserving of human rights. Both terms are deeply racist and stem from white supremacy as is evidenced by the fact that “illegals” is almost exclusively reserved by those who employ the term for black and brown immigrants and refugees.
When you think of human persons as “illegals” as opposed to full human beings, your mind can quickly go to places like “they don’t need beds, toothbrushes, and showers,” or “if they didn’t want to be separated from their children, they shouldn’t have come here” or “they don’t deserve basic medical care,” or “if coming here results in their death (even if the death occurs while in U.S. custody), then that is on them.” Describing persons as anything less than human has proven over and over again to lead to treating persons as less than human, often resulting in horrific suffering and sometimes resulting in the death of millions of persons.
In the ongoing tug of war with white supremacy, we must reject all language that dehumanizes anyone, and this means rejecting the language of referring to persons as “illegals,” thus relegating such words to the racist trash heap of history where terms like “illegals” and the “n-word” belong.
One World House - Mark Davies 
Very well stated. I wish more people understood.
Years ago a colleague of mine in the United Methodist Church went to visit Numbers USA, an anti-immigration organization founded and run by a faithful United Methodist. A plea was made to the organization to cease using ‘illegal alien’ as their preferred term in favor of ‘undocumented immigrant.’ The point was made that since Numbers USA’s focus was on the supposed environmental damage caused by population growth then it made no difference which term was employed and that obviously ‘illegal alien’ was a pejorative term. The organization rejected the plea of my colleague.