WASHINGTON — As the manhunt for the Boston bombers reached its climactic conclusion, Americans of all hues and backgrounds heaved a sigh of relief. Thank goodness it wasn’t … fill in the blank:

A white Christian from the South;

A dark-skinned Muslim foreigner;

An illegal Latino immigrant.

Thank goodness.

The marathon terrorists it turns out were of a Chechen background. Huh? Is that, like, in Czechoslovakia or something?

If many Americans had forgotten or never known where Chechnya is — or that Czechoslovakia is now the Czech Republic — they were not confused when it came to the Muslim connection. The mere fact that the brothers, Dzhokhar and Tamerlan Tsarnaev, were connected to Islam was sufficient for some to justify holding all Muslims in suspicion.

The relief, meanwhile, was that “our” demographic group wouldn’t this time be blamed. Even darker-skinned Muslims, familiar with group demonization following 9/11, reportedly were relieved.

As police pursued the bombers, a friend asked me which I would prefer: A domestic or foreign terrorist? Putting aside the unfortunate nature of the question (obviously one prefers neither), I answered foreign, explaining: “Foreign enemies unite us; domestic enemies further divide us.”

This blurted observation has been proved true enough times in the past to qualify as a reasonably defensible proposition. But even domestic terror now divides us. Us-Them has become far more complicated as we have become far more diverse. The Tsarnaev brothers have shuffled our templates into something that eludes easy characterization and denies us the unifying enemy that at least provides a sense of something that can be fixed.

Whom do we hate when the enemy is a composite of our own diverse ecosystem? When “them” is “us?”

Our Boston (alleged) mass murderers were foreign-born but the younger brother is an American citizen. (The older brother, who died in a police shootout, was a permanent resident.) Given the fact that one in eight U.S. residents is foreign born according to the Census Bureau, it is difficult to infer that being foreign-born makes one more likely to become an anti-American terrorist.

The brothers also were Muslim, but so are 2.75 million others living in the U.S., 63 percent of whom are foreign-born, according to the Pew Research Center. Again, it isn’t possible to characterize an entire religious group by the actions of two individuals who claim to belong to a certain religion. Most Christians don’t wish to be identified with the random Bible-quoting ranter (think Westboro Baptist Church’s crusader) any more than a majority of Muslims want to be grouped with radicals who also claim Allah as their guide.

That said, there can be no denying that radical Muslims vastly outnumber those in Christian or other religious groups who believe that killing infidels is a ticket to eternity. It isn’t easy to get from “turn the other cheek” to jihad, notwithstanding the Crusades or the Gainesville, Fla., “preacher” who burned a Koran, proving only that followers of the Christian faith have no monopoly on intelligence. Even a tiny percentage of 1.5 billion Muslims, or 21 percent of the world’s population, who have embraced jihad is enough to give pause. Moderate Muslims share that pause.

Alas, this is not a comparative religion seminar but an examination of the difficulties ahead as we wrestle acquired biases into submission and resist the urge to demonize groups of people. Discrimination is a life-saving tool in the jungle — steer clear of the hyenas — but it has no place in American jurisprudence. An American citizen gets the full slate of equal rights and responsibilities, including a presumption of innocence, no matter which God he invokes.

Thus, though it is tempting to declare the surviving Boston bomber an “enemy combatant,” as suggested by Sen. Lindsey Graham, R-S.C., it is essentially a means to deny rights accorded any other American citizen who commits a crime. The only justification now would be that the Boston bomber is believed to be Muslim, which isn’t a crime, or that he and his brother may have found inspiration among others of like intent.

Once we begin to discriminate in the assignment of rights to citizens and legal residents based on their thoughts, religious affiliation, assemblage — or our own assumptions — we risk becoming our own worst enemy.

At this juncture, the light-skinned, foreign-born, Muslim-leaning brothers who reigned terror on Boston fit neatly into no category we can define with certainty other than evil, which is, sadly, the unique provenance of the human race. Rooting it out will require more than tighter security or better immigration laws.

Kathleen Parker is a Washington Post columnist. Her email address is kathleenparker@washpost.com.