John LaFarge Jr. SJ (February 13, 1880 – November 24, 1963) was an American Jesuit Catholic priest known for his activism against racism and anti-semitism.

[5]: 147  He moved into pastoral work, spending fifteen years (1911–26) ministering to mainly African-American and immigrant communities in rural St. Mary's County, Maryland, along Chesapeake Bay.

[8] In 1926, LaFarge left his pastoral work in Maryland to become assistant editor of America, a leading Jesuit weekly magazine in the United States.

[8] He described himself as a priest who was also a working journalist, someone whose main task it was to study the events of the day and to connect them with deep moral and theological questions.

[citation needed] In 1937, LaFarge published what would become his most important book on racism, Interracial Justice: A Study of the Catholic Doctrine of Race Relations.

One of the people impressed by LaFarge's arguments was Pope Pius XI, who invited him to secretly prepare an encyclical on "racialism", the topic he considered to be the "most burning".

Entitled Humani generis unitas ("On The Unity of the Human Race") from its first three words, it was drafted during the summer of 1938 and given to Pius XI near the end of the year.

It encompassed a general critique of modern ideas such as the state and race that have diminished human dignity and argued against the moral evils of racism and anti-semitism.

For several decades, it remained in obscurity in the Vatican Archives until researchers Georges Passelecq and Bernard Suchecky brought the it to light in the 1990s.

In 1947, LaFarge was invited to give the prestigious Dudleian lecture at Harvard; he chose for his topic "juridic wholeness," arguing that human rights must apply universally and not just to select groups.