I tend to disagree, at least in part

It was an outrage from the rest of humanity that made some backward countries like Mauritania finally ban slavery, but the first impulse was purely economic as I get it. Slavery ended not due to the lack of slaves but simply because slave labor was crowded out by more efficient mechanized labor which required highly skilled workers (in comparison with what slaves are generally required to know and do), which is hardly compatible with slavery. The public hostility toward slavery was mostly a side effect which emerged later (cp. industrialized Union states vs agrarian Confederate states in the period of the American Civil War)

In the late 17th century, the Roman Catholic Church, taking up a plea by Lourenco da Silva de Mendouca, officially condemned the slave trade, which was affirmed vehemently by Pope Gregory XVI in 1839. An abolitionist movement only started in the late 18th century, however, when English and American Quakers began to question the morality of slavery. James Oglethorpe was among the first to articulate the Enlightenment case against slavery, banning it in the Province of Georgia on humanist grounds, arguing against it in Parliament, and eventually encouraging his friends Granville Sharp and Hannah More to vigorously pursue the cause. Soon after his death in 1785, they joined with William Wilberforce and others in forming the Clapham Sect.[1]