Washington — The ouster of Department of Homeland Security Secretary Kirstjen Nielsen — the implementer of some of the most unjust immigration policies since the internment of Japanese Americans during World War II — is another proof of Donald Trump’s ratchet-wrench theory of loyalty. It goes only in his direction.

In the end, the burnt offering of a staffer’s character is not enough. After trying to enforce and anticipate Trump’s cruel or irrational whims, he or she is generally packed off without ceremony, with diminished professional respect and, presumably, with diminished self-respect. Trump has taken what should be the honor of a lifetime — serving the country at the highest levels of the executive branch — and turned it into a reputational black hole.

A few — think former Defense Secretary James Mattis and former United Nations Ambassador Nikki Haley — have managed to serve without self-immolation. But this is only because they skillfully established some distance between their views and the president’s. Did anyone doubt that Mattis respected NATO, or that Haley was concerned about human rights?

Nielsen, however, took another route. After a career generally characterized by competence, Nielsen chose to reflect Trump’s priorities. Maybe she reasoned to herself that she was implementing the president’s agenda more humanely than others would have done. Aristotle referred to human beings as rational animals. They are, at least, rationalizing animals.

But the separation of crying migrant children from their parents as a deterrent, and the storing of children in prison-like conditions, will be some of the most enduring political images of the Trump era. It says something about Nielsen that she took part in such practices. It says something about Trump that such actions were apparently too moderate and restrained for his taste.

The status of immigration as Trump’s defining issue is still confusing. He returns to this topic in nearly every time of political stress. Yet it is difficult to imagine that his convictions are deeply rooted. Trump has a long history of hiring illegal immigrants, whom he clearly did not regard as potential terrorists and rapists. And it wasn’t too long ago that Trump criticized Mitt Romney for intemperance on the topic as the Republican presidential nominee. “He had a crazy policy of self-deportation, which was maniacal,” Trump said following the 2012 presidential election. “It sounded as bad as it was, and he lost all of the Latino vote. He lost the Asian vote. He lost everybody who is inspired to come into this country.”

But now Trump seems to find a message of exclusion positively invigorating. In his stump speech, he does not raise legitimate issues related to immigration. Instead, he easily outpaces Romney in the maniacal and crazy department. At the White House, he humiliates staffers who don’t share his enthusiasm and fires people who are not creative enough in their severity. Even a hint of reluctance is taken as betrayal.

The explanation cannot be purely political, at least from a Republican perspective. Trump carried a simplified version of these ideas into the 2018 midterm election — claiming that brown people were invading the country and suggesting that they should be shot by the U.S. military. One outcome was the loss of 40 Republican House seats.

But Trump — the ultimate political narcissist — cares not one whit for the political fortunes of the GOP. He cares only about his political standing within the GOP. It is 85% to 90% support among Republicans that ensures the servility of senators and House members in opposing various investigations of Trump and his administration. And this support forestalls the possibility of a serious nomination challenge in the upcoming presidential election.

I have no doubt that Trump is using the issue of immigration in a cynical way to solve political problems. But the implications are disturbing. Trump clearly regards resentment against migrants as the common, binding purpose of the GOP. And so far he has not been wrong. The success of Trump’s cynical ploy depends on the existence of genuine enthusiasm for exclusion within his party. His play only works if GOP nativism is broad and authentic.

In the recent political past, these convictions were usually latent. Anti-immigrant Republicans such as Pat Buchanan and Tom Tancredo were generally viewed as cranks. And more visionary Republicans such as Jack Kemp or George W. Bush emphasized the economic contributions and positive social values of recent migrants.

But Trump’s appeal to inner demons above better angels proved easier than many of us hoped. And that makes the political and moral damage harder to repair.

— Michael Gerson is a columnist for Washington Post Writers Group.