The church's stance that a baptized child is irrevocably Christian was established nearly a century before the Holocaust, when, in 1858, papal guards took Edgardo Mortara, 6, from his family in Bologna when word spread that he had been clandestinely baptized by a Catholic maid.
"in 1858"
Oh, yeah? Well, in 1877, a Jewish person in lower Moldavia made a disrespectful remark about the wood carvings in a church in upper Slobbovia, so I guess that tells you all you need to know about Judaism.
Schmendrick.
It existed long before that, actually.
papal guards took Edgardo Mortara, 6, from his family in Bologna when word spread that he had been clandestinely baptized by a Catholic maid.
Young Mr. Mortara was in danger of death at the time, but recovered.
It was actually against the law at the time for a Jewish family to employ a Catholic domestic, in part to prevent exactly this situation from happening.
Edgardo was raised personally by Pope Pius IX as though he were the Pope's own son. When offered the opportunity, at age 18, to renounce his Catholicism, he refused. He later became a priest and wrote a book effusively praising Pius IX.
(Just some additional details about the story you may not have heard.)