From the perspective of those in the 16th century, the development of race was meant to separate those perceived to deserve power from those who were perceived not to. By classifying different phenotypical features, it simplifies the ideas of the elite, civilized, righteous group (whites) are superior to the simple, uncivilized/uncultured, inferior group (people of color). However, this means of social organization is rather unnecessary from my perspective. Race simplifies groups based on the color of skin, but if one is going to attempt to dominate another group, race would cause for missed opportunity to exploit even whites. If your goal is to assign groups to varying social status and occupations, it seems that something similar to the caste system would be more appropriate.
While the caste system comes from a cultural belief that a person's actions of a past life dictate the standing of their next life, I think a similar idea could be put into place. The dominant group could argue that those too simple or financially/socially challenged were being divinely punished for their sins. Therefore, those who are not pious enough to the right, true God are undeserving of their land, resources, or human rights. Individuals then could be cast into various social positions based on the idea of divine influence in their lives.
Albeit, this mindset is closer to a more Medieval era one than a colonial or civil one, the later influence of religion and the idea of the new frontier is difficult to ignore when Manifest Destiny begins to eventually comes into play with American's migration to the West.
If divine presence had been used previously as a means of control and social order, why not use it again? America loved to tout that it was a religiously free nation, however, right into the cusp of the 20th century, there was still religious discrimination in the public sphere, even so far as to specific versions of the bible being used in the public school curriculum that certain sects of Christians were forbidden to read. Through religious social organization, it would make for a more profitable system of injustice. The poor would always be challenged to be more devote, as to reap the divine rewards, while the rich could still profit off of the poor and remain the highest class for being the exemplars of their religion.
