Slavery
Slavery, in one form or another, has been present among the goodly races on the Mainland since at least since the Age of Demigods, though ancient epics from the Time of the Eight and the First War describe the use of slaves by servitors. Some sages theorize the goodly races, in fact, adopted the practice from servitors. In the earliest days after the Battle of Sacrifice, slavery among humans was generally enacted as a punishment for debt or criminal activity, while the Dwarves instead subjugated weak servitor races.
When Hadrian Ubrekt, ruler of the Ubrekti Empire, conquered the neighboring city of Tyros, he enslaved and force-migrated most of its residents, leading to a fundamental change in the nature of the practice. Within half a century, slavery had become integral to the life of the empire, so much so that when Hadrian's son, Diocelt, laid siege to Crad in 2797 BI, between one-third and one-half of his army was slave levy.
Slavery was most widely practiced during the First Empire, and played no small part in the ascent of Ubrekt over its rivals, but the practice lead to a great number of uprisings, and led to a general sense of paranoia among the Ubrekti nobility that, in part, explains some of their more bizare and cruel behaviors. During the Wars of Fracture, the practice began to wane, as freed territories were loathe to keep their kinsmen in bondage. In most areas, particularly Flannary, slavery grew into serfdom, though it it is worth noting that slavery is still an essential part of Petran culture and economic life, though it is apparently bound by complicated religious rules and has grown into a practice something closer to extended indentured servitude. Outright slavery was still practiced in the City States of Alexandria's time, and several of the First Stand's military action began with a fomented slave rebellion vanguard.
As such, the Alexandrian faith - and it's recent offshoots - universally disdain slavery of other "goodly races."
Dwarven Slavery
For many centuries after the formation of the Alexandrian church, Slavery was still practiced among Dwarves. As it had always revolved around the lessor servitors, and because the Dwarves were an important partner in building the early Church, the practice was tolerated. During the Cleansing Wars, rather than exterminating servitor settlements and warrens, dwarves captured and enslaved the women and children, pressing them into service, generally as agricultural laborers, a position enslaved servitors almost monopolize in modern Gildenhome. The practice extends almost exclusively to kobolds and goblins, as larger servitors are too simply too dangerous to adequately control, though War College Fortress was built with the help of arcanically enslaved giantkin. Over the centuries the subjugated Kobolds and Goblins did most resource production tasks in the Clanhomes.
Since the Servitor Uprising that lead to the Gnomish-Dwarven war, the practice has fast fallen out of favor and in many clanships specifically banned. In some areas, Dwarves have made it their focus to renew their ancestral connection with the land while other areas have opted to bring in sojourning humans and confine them to special enclaves for specific periods of indenture.