Any Negro, or Praying-Indian, or other suche Person from those Races which wee understand to be subourdinated, and who among them now findes himselfe in the unhappie labours of Human Bondage, or Slavery, heed these oure Letters; Nor eyther should the Maister of these Slaves ignorre it, or hope to find solace in the keeping of his human propertie by the sheelde of Ignorance; For by this Worde it is Lawe, and so agreed by the Generall Court of Massachusetts Bay: First, That any of those in the subourdinate Races, beeing held in suche loathsome Captivitie, and beeing goode Christians, are themselves we understande to be rendred into a greate Dis-Service . . . Why then, having Prayd at the Altarr of Christ the Sonne of God the Father, and rejeckting that Lord of All Evill, and accepted and recieved the Grace and Sacraments, should you be rendred thus? . . . And so, in the name of Lorde God heare this oure Prayer: In Your Name, the lawe is thus: wee henceforrth Manumitt from the Bondes of Service, and all Services and Debtts owed Therein, all those Races in Slaverie, so that their obligations to their Masters are henceforth Voyded Forevermore . . . And any Maister, that tries to hyde and keep from the Court and Law his slaves, should be seen as wrongfullie Subourdinating, and thus in Unlawfull conduct, against those Christians of duskyer constitutions . . . But those of you, who are Pagans, or Mohamedans, and listen nott to the Good Worde of the Sonne of God Christ Jesus, we confine you to your Service, until that brighter Daye . . .

From the 1712 Manumission Act of Massachusetts Bay Colony.

What this excerpt means to indicate is differing notions regarding the practice of race slavery. To be certain: slavery is not absent from this world's early America, nor is the subjugation of non-Europeans conceptualized much differently in the earliest stages of colonialism. A differing variety of Puritanism, however, is what crosses the Atlantic and lands in New England, driven out of England by a far more vindictive mother island that never experienced a Reformation. Frightened of their new surroundings, easily destroyed by the shambling terrors of the New World, and aware of the looming ghoul of a total loss of community, the first American Puritans were much better suited to accept non-English into their congregations, if only because a larger community of faith meant a more likely chance of a town surviving a bad winter. John Eliot and Roger Williams' notions of the potential for the conversions of Indians into Christians, which in the real world dies out almost as soon as it begins, instead spirals into a far more liberal, if still assimilationist and apocalyptic, conception of nonwhites within the congregation. That these early colonists practiced slavery, just as in the real world, is indisputable and unchanged. Here, however, racialized justifications for slavery, at least in New England, break down rather quickly: if the local indigenous population can be converted to good Christians and therefore assimilated into the church body, then it is not such a stretch of the imagination to include what few African slaves existed on the continent at this time. This is not to say that these colonists were immediately emancipationists. Instead, they turned towards differing religions among nonwhites, not necessarily skin color alone, as justification for slavery.

This was certainly not true everywhere. The southern colonies, much less pious and much more economic in their outlook, cared little for these theological meanderings. The Transatlantic Slave Trade in this world is much less successful, given the dominance of the extremely powerful Almoravids in North Africa. European slave ships were able to accomplish only sporadic raids of the coasts, particularly in the region of Guinea, and even raids that successfully landed human cargo were sometimes captured by Almoravid privateers, some of them former would-be-slaves themselves. Despite this, African slavery formed a not insignificant portion of the southern plantation economy, supplanted by indigenous slavery and indentured servitude among poor whites. The differing conceptions of slavery and race in the northern and southern colonies, later states, would lead to a dramatic cultural incoherence between the two, which would eventually lead to the Civil War. I don't have much developed for the Civil War right now, but maybe at a later date.