Another decree, Romanus Pontifex (1455), reinforced what later became known as the “Doctrine of Discovery,” a framework used to justify colonial expansion and the enslavement of Indigenous peoples across Africa and the Americas.

These permissions granted under Pope Nicholas V were later upheld by subsequent pontiffs, including Pope Callixtus III, Pope Sixtus IV, and Pope Leo X.

Although the Vatican officially rejected the Doctrine of Discovery in 2023, critics say it stopped short of formally cancelling the original papal bulls that authorised enslavement and conquest.

In the encyclical, Pope Leo XIV also admitted that the Church was slow to recognise slavery as fundamentally incompatible with Christian teaching.

“The church has long affirmed the dignity of every human being as the basis of its doctrine, even if it took eighteen centuries for its full incompatibility with slavery to be explicitly recognized,” he wrote.

“This constitutes a wound in Christian memory, one from which we cannot consider ourselves detached.”

The Pope, the first American-born pontiff, is also reported to have ancestral links to both enslaved individuals and slave owners, according to genealogical research published by scholar Henry Louis Gates Jr.

The findings suggest that at least 17 of his American ancestors were recorded in historical documents as Black, Creole, mixed-race, or free people of colour.

Reactions to the apology have been largely positive among scholars and Black Catholic advocates, who described it as a significant but overdue step.

Anthea Butler, a senior fellow at Oxford University’s Koch History Center, said the apology was necessary for the Church’s credibility in addressing modern exploitation linked to technology.

Jesuit priest and academic Christopher J. Kellerman also welcomed the statement, though he said deeper historical clarification is still needed.

“Pope Leo has strengthened the moral credibility of the church with this admission and apology today,” he said.

“Hopefully a future document will explain in more detail the church’s involvement with slaveholding.”

Earlier pontiffs, including Pope John Paul II, had previously apologised for the participation of Christians in slavery during visits to African countries such as Cameroon and Senegal.

However, this encyclical marks the first time a pope has directly acknowledged the Vatican’s institutional role in legitimising slavery through official Church doctrine.