[1] He was one of the architects of Nostra aetate or "In Our Age," a declaration which was issued by the Second Vatican Council in 1965 and which repudiated antisemitism.
[2] Oesterreicher was born to a Jewish family in Město Libavá (Stadt Liebau) in Moravia (then part of Austria[3] and now the Czech Republic).
In 1934 he founded the newspaper Die Erfüllung (The Fruition) to improve relations between Jews and Christians and to fight against antisemitism.
[2][6] Oesterreicher edited a document authored by Waldemar Gurian (a Russian-Jewish convert to Catholicism) and Karl Thieme (a German-Lutheran convert to Catholicism) in 1937 entitled "The Church of Christ and the Jewish Question", which called on all Christians, but especially the Pope and the Roman Curia, to oppose contemporary anti-Jewish sentiment and to take a public position on the movement against the Jews in Germany.
[2][9] The statement rejected antisemitism and repudiated the notion that Jews were responsible for the persecution and death of Jesus Christ.
His books include The New Encounter Between Christians and Jews; Racism, Anti-Semitism, Anti-Christianism; and God at Auschwitz?.