Azurara's principal justification for the enslavement of the African captives, and one to which he returns frequently throughout his Chronicle, is the salvation of the captives' souls through their introduction and conversion to the Christian faith. The captives' souls, he says, have been saved by separating them from their families and bringing them to Europe, and their descendants would also be saved for all the generations to come.

Although he realizes that not every captive will have converted to Christianity, Azurara says at the end of his narrative that he believes the majority of the 927 slaves brought to Portugal as a result of the voyages he describes "were turned [to] the true path of salvation." He regards this as the greatest achievement of the expeditions and as justification for everything they did.

Azuzara also regards it as a more general benefit for the slaves to have been taken from an uncivilized country and brought to Europe. Beyond this, he frankly states that the main justification for slavery is the great benefit the slaves have brought to their captors and the enrichment of Portugal by their capture. He also refers to the honor these expeditions have conferred on Portugal by the courage and hard work of those who took part.