Pope Francis’ planned visit to Auschwitz on Friday, to pray at the site of the Nazi concentration camp, is sure to be a sober occasion. The presence of the leader of the Catholic Church will once again call attention to one of the 20th century’s worst atrocities, and serve as a reminder of the terribly high stakes for those who would make peace in the world. As Pope John Paul II said in 1979 when he became the first sitting Pontiff to visit Auschwitz, “Not only those who directly bring about wars are responsible for them, but also those who fail to do all they can to prevent them.”

But, when it comes to the Vatican and the Holocaust, history lends an extra layer of meaning to Papal recognition of what Pope John Paul II called the “place built on hatred and on contempt for man.” (Pope Benedict XVI also visited the site in 2006.)

During World War II, the Vatican’s reaction to Nazi crimes was seen, at least by American media like TIME, in a positive light, especially considering the Vatican’s location within Axis-aligned Italy. TIME reported in 1942 that the late Pope Pius XI had called what the magazine euphemistically termed “anti-Jewish excesses” the “Sacrifice of our Father Abraham”—and that the current Pope, Pius XII, “neither understands nor approves” Nazi persecution of Jews. As the war wound to an end, in 1944, Pope Pius XII was praised by Rome’s chief rabbi for the work the Vatican did to help Rome’s Jews while the Nazis occupied the city.

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In the early 1960s, however, the German playwright Rolf Hochhuth brought Pius XII’s wartime actions back into the headlines with a new play, the title of which was rendered in English as The Deputy. In the play, Hochhuth put forward the argument that Pius actually saw Nazi Germany as an acceptable barrier between the atheist communist world and the Christian world, and that if he had truly wanted to stop Hitler from killing Jewish people he could have been perhaps the only man in the world who would have been capable of doing so with his word alone. TIME summarized the uproar thus:

[The] legitimate attacks on Hochhuth’s portrayal of the Pope sidestep the key question raised by his play: Why did Pius XII, who condemned the aerial bombing of civilian centers and the postwar aggressions of Communism, not explicitly attack the liquidation of Europe’s Jews? The issue has intrigued many modern historians, since Pius clearly detested Hitler’s totalitarianism as much as he loved the German people. He helped draft Pius XI’s encyclical Mit Brennender Sorge (With Burning Sorrow), which condemned Nazi racism in 1937. When the Germans organized a roundup of Roman Jews in 1943 and 1944, the Pope made no formal protest, but allowed convents and monasteries to take in refugees, and offered 50 kilograms of gold to ransom the lives of 200 Jewish leaders. In Hungary and Slovakia, both predominantly Catholic countries governed by Catholic Nazi puppets, his papal nuncios had some success in halting the deportation of Jews to Polish death camps. Yet Pius ignored Allied pressure to speak out against Nazi genocide. In the autumn of 1942, Myron C. Taylor, Franklin Roosevelt’s personal representative to the Vatican, gave the Holy See evidence of the anti-Jewish campaign, and the U.S. Minister to Switzerland warned the Vatican that failure to condemn these atrocities ‘is undermining faith both in the church and in the Holy Father himself.’ Baron Ernst von Weizsaecker, who claimed that he tried to protect the Pope from Hitler’s wrath while serving as German envoy to the Holy See, cabled his Foreign Ministry superiors: ‘The Pope has not allowed himself to be forced into any demonstrative utterances against the deportation of the Jews.’ Jesuit Leiber admits that Pius ‘found it difficult’ to speak out clearly against the murders, but adds, ‘This was providential. Otherwise, I fear greater harm would have been the result.’ Catholics point out that after the Dutch bishops issued a joint pastoral letter attacking the deportation of Jews, the Nazis retaliated by arresting Catholic converts from Judaism. In 1942 Cracow’s Archbishop Adam Sapieha pleaded with the Vatican not to broadcast accounts of German atrocities since it would only make things harder for his people. The best evidence of Pius’ own judgment is his 1943 letter to Berlin’s Bishop Konrad von Preysing: ‘We leave it to the pastoral leaders on the spot to weigh whether and to what degree the danger of retaliation and pressure in case of remonstration by bishops make it appear advisable to exercise restraint to prevent greater evil, despite the listed grievances. Here lies one of the reasons why we ourselves impose limitations on ourselves in our public utterances.’

Debates about the culpability of Pius XII continued for years. By 1976, TIME reported that at least six books had been written on the Pius question and that in response Pope Paul VI was overseeing the publication of the Vatican’s own history of its wartime actions. At the time, the latest volume was reported to showcase the Vatican’s “attempts in 1943 to help Jews in Rumania, Bulgaria, Yugoslavia, Poland and Italy” but also not to answer all criticisms. “The conflicting views make only one thing clear: the facts have begun to fall into place, but there is as yet no consensus on the behavior of Pius XII,” the magazine noted. “If anything, [the new volume] has heightened the debate rather than resolved it.”

Meanwhile, however, the relationship between the current Church and the Jewish people generally improved.

In the early 1960s, the Vatican Council addressed an agenda chapter about Jews—which, as TIME reported, was introduced because a Cardinal wanted to prevent a repeat of the Nazi use of Christianity as a justification for persecution of Jews. The idea was the formally clear the Jewish people of any responsibility for the death of Jesus Christ. In 1965, the Vatican Council voted to approve a statement that said that: “What happened to Christ in his Passion cannot be attributed to all Jews, without distinction, then alive, nor to the Jews of today” and rejected “hatred persecutions, displays of anti-Semitism directed against Jews at any time and by anyone.'”

When Pope John XXIII was named TIME’s Person of the Year for 1962, his sympathy toward Jewish victims of Nazi violence was cited as one of the qualities that made him worthy of his mantle. In 1986, Pope John Paul II became the first sitting Pope to visit a synagogue—a visit during which he took care to specifically mention the Church’s “abhorrence” of the Nazi genocide. The following year, he further healed old wounds by issuing a papal letter on the topic of the Holocaust. “While the letter was ostensibly routine, its language was heartfelt,” TIME reported. “‘Christians approach with fearsome respect the terrifying experience of the extermination, the Shoah, suffered by the Jews during the Second World War,’ wrote the Pope, ‘and we seek to grasp its most authentic . . . meaning.’ He went on, ‘Before the vivid memory of the extermination . . . it is not permissible for anyone to pass by with indifference.’”

When conflict arose in the late 1980s over a Carmelite convent situated at Auschwitz—which TIME noted “struck Jews and even some Catholics as an insensitive intrusion into a setting that will forever symbolize the Holocaust”—and Poland’s Roman Catholic Primate issued a statement that was widely seen as anti-Semitic, John Paul II personally intervened to help resolve the conflict. (His replacement, Benedict XVI, however, “raised eyebrows” for what some saw as his painting the Holocaust as a crime against Christianity, and for failing to mention anti-Semitism during his speech on his own visit to Auschwitz.)

It may be impossible to ever fully settle the question of whether the Vatican did the right thing during World War II. But what the Church now thinks about Nazism is, especially this week, clear.

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Write to Lily Rothman at lily.rothman@time.com.