Earlier this summer, to great fanfare, Pope Francis apologized for the Catholic Church’s role in the colonial invasion of the Western Hemisphere and the violent subjugation of its indigenous inhabitants. “Many grave sins were committed against the Native people of America in the name of God,” he told a gathering in Bolivia. “I humbly ask forgiveness, not only for the offense of the church herself, but also for crimes committed against the native peoples during the so-called conquest of America.”

On the issues of climate change and economic inequality, and to a lesser extent on issues related to sexuality and social mores, the so-called “radical pope” has made immense progress in improving the tone of the Catholic Church’s communications with the rest of the world. He has brought a new relevance to the church by emphasizing the ongoing nature of the exploitation he admitted to and denounced in Bolivia, and by refocusing the notoriously Italocentric institution’s orientation to Latin America and the Global South.

Yet when he visits the United States next week, the pope will commit a grievous and historical error, one for which some super-“radical” pope of the future will have to apologize in turn. On Wednesday, at the Basilica of the National Shrine of the Immaculate Conception in Washington, DC, Francis will canonize Father Junípero Serra, the founder and most famed symbol of the system of missions in the Spanish colony of Alta California.

Born in Spain, Serra arrived in Spanish-held Mexico in 1749 and quickly set about working for the Inquisition, citing by name several natives who refused to convert to Christianity; they were guilty, he wrote, of “the most detestable and horrible crimes of sorcery, witchcraft and devil worship.” Serra soon gained control of the missions of Baja California, but he found that the native population had already been nearly extinguished by contact with the Spanish. Looking for fresh converts, he led expeditions up the coast into the present-day state of California, where he settled at Monterey and set up ten new missions to spread the gospel through the new land.

From their establishment in the late 1760s until Mexico declared independence and secularized them in the 1820s, the California missions formed a network of forced-labor camps and, in effect, slaughterhouses, where the once-vibrant native peoples of California were systematically reduced to mere shadows of their former selves: Under the mission system, the overall indigenous population of Southern California declined by nearly 1,000 every single year.

If they were lucky enough not to be killed by European diseases spread largely through sexual violence on the part of the Spanish, many natives at the missions sought to run away, not terribly unlike African slaves on the East Coast in the United States. According to Carey McWilliams (editor of The Nation from 1955 to 1975), in his classic 1945 book Southern California: An Island on the Land, the missionaries didn’t even much mind runaways, because that gave them a reason to go on fugitive-hunting expeditions to distant villages from which they could round up more natives and bring them back to the missions.

“With the best theological intentions in the world,” McWilliams wrote, “the Franciscan padres eliminated Indians with the effectiveness of Nazis operating concentration camps.”

Some defenders point to a smattering of evidence that Serra was not the most sadistic Spanish colonial overlord in California at the time—Pope Francis is likely to argue or imply as much at the canonization ceremony—but there is just as much proof pointing in the other direction. “That spiritual fathers should punish their sons, the Indians, with blows appears to be as old as the conquest of these kingdoms,” he wrote to one governor of the territory. In the early 1780s, according to McWilliams, another governor actually filed a complaint against Serra for sanctioning the harsh treatment of native converts.

Another typical argument in favor of Serra’s canonization is that we shouldn’t judge the misdeeds of the past according to the standards of the present. But this too is rubbish: Anyone who makes that argument regarding the renaming of schools and other public sites to rescind tributes to slaveholders and white supremacists is properly labeled a racist and an apologist for the worst that humans have ever done to other humans. Should Pope Francis get a free pass to canonize a man directly responsible for the brutalization and ultimately the near-extinction of an entire people simply because it is, in some warped public-relations sense, a tribute to Hispanic Americans, a growing constituency in the Catholic Church?

The summer that is ending saw the beginning of what many of us only a few months ago thought impossible: a serious and fairly intelligent national debate about the legacy of slavery and the Civil War. The proposed canonization of Serra has gained some attention on the West Coast, but almost none in the East. That is because in their grade-school history classes the students of California learn something the rest of us do not: There was not one form of slavery in the territory that is now the United States. There were at least two.

How absurd it would be to congratulate ourselves on the removal of the Confederate battle flag from state capitols and Walmart shelves and to permit the pope to sanctify a man complicit in, and responsible for, the eradication of entire cultures and civilizations. “So far as the Indian was concerned,” McWilliams wrote, “contact with the missions meant death.” Some radical, to make of Satan a saint.