Difference of race or condition or sex is indeed taken away by the unity of faith, but it remains imbedded in our mortal interactions, and in the journey of this life the apostles themselves teach that it is to be respected, and they even proposed living in accord with the racial differences between Jews and Greeks as a wholesome rule.
St. Augustine’s is the earliest known interpretation of the socio-cultural dimension of this verse. He evidently understood the text in the exact opposite way that it is understood within the modernist egalitarian paradigm. This interpretation set the tone for the Church’s understanding of the reality of biological differences in terms of gender and race for 1500 years.
It is interesting that Augustine notes the respect of racial distinctions to be a New Testament teaching, in contradistinction from the popular contemporary understanding of Old Testamental racial distinctions as having been undone by Pentecost. Augustine explicitly cites the apostolic proposition and practice of respecting cultural differences, but it is probable that when referring to apostolic teaching, he had a text like Acts 17:26 in mind. The post-Enlightenment understanding of Galatians 3:28 as undoing distinctions in terms of race and gender, is in fact a revival of a gnostic anthropology condemned as heresy by all the fathers of the church, including St. Augustine himself.
While it seems as though Augustine wouldn’t go as far as embracing the reality of race even as a post-mortal heavenly reality, he was certainly a proto-kinist in terms of his understanding of race and nationhood.