The papal bull 'Sicut Dudum' was issued by Pope Eugene IV in a significant move to protect the Guanche people of the Canary Islands from enslavement by Spanish colonizers. The Pope emphasized that any Guanche who had accepted Christianity or was in the process of conversion should be treated with dignity and respect. The Canary Islands had become a focal point in the Spanish expansion into the Atlantic, and with the growing wealth generated from sugar and other plantations, the demand for labor was increasing. This situation posed a grave danger to the indigenous populations, who were often forced into servitude or harsh working conditions.

By articulating the prohibition against the enslavement of newly Christianized Guanche, the Pope sought to assert moral authority over the colonizers and highlight the importance of converting indigenous peoples to Christianity without subjecting them to exploitation. The decree served as both a protective measure and a philosophical stance against the unjust treatment of natives, aligning with the Church's broader missionary goals across the globe.

This papal decree was pivotal, as it not only clarified the Church’s position on the rights of newly converted natives but also shaped the legal and moral frameworks within which the Spanish colonizers operated. As the Spanish Crown was expanding its influence in the New World, that framework would undergo various interpretations, which influenced later colonial policies and indigenous rights discussions. Meanwhile, it also made clear that efforts at conversion should be paired with ethical considerations for the welfare of the indigenous populations.