On Sunday Francis became the third pope to visit the Grand Synagogue of Rome. Welcoming the Pontiff, Rabbi Riccardo Di Segni noted that, according to rabbinic tradition, “an act repeated three times becomes chazaqà, a habit”. By following in the footsteps of John Paul II and Benedict XVI, Francis has confirmed that it is a custom for the Bishop of Rome to visit the city’s main synagogue. During his visit Francis spoke of a “veritable transformation of Christian-Jewish relations in these 50 years”. We have become so used to healthy relations between Catholics and Jews that it is easy to forget that the relationship was toxic for most of the past 2,000 years. What happened 50 years ago? The fathers of the Second Vatican Council issued Nostra Aetate, a declaration on non-Christian religions. On Sunday, Francis offered a pithy summary. The text, he said, “has indicated the way: ‘yes’ to rediscovering Christianity’s Jewish roots; ‘no’ to every form of anti-Semitism and blame for every wrong, discrimination and persecution deriving from it”. Two developments last month suggest that Catholic-Jewish ties can be deepened further. On December 3 Orthodox rabbis from Europe, Israel and the United States issued an unprecedented statement, declaring that Christians and Jews have a “common covenantal mission”. The document also acknowledged “the ongoing constructive validity of Christianity as our partner in world redemption”. Then on December 10 a Vatican commission issued a theological reflection which underlined that “the Catholic Church neither conducts nor supports any specific institutional mission work directed towards Jews”.