In summary, the Noahic covenant of Genesis 8: 20– 9: 17 constitutes the formal establishment of the common kingdom. This means that God himself established and rules the common kingdom. It exists under the lordship of the triune God— Father, Son, and Holy Spirit. The common kingdom is not in any sense a realm of moral neutrality or human autonomy. During the early history recorded in Genesis 4 cultural commonality existed alongside a spiritual antithesis. God put an end to that cultural commonality when he separated Noah’s family from the rest of the human race at the time of the flood, but after the flood he reestablished that cultural commonality by means of a covenant. For the rest of the history of this world God ordains that the cycles of nature will continue in regular patterns, and that all people— whether believer or unbeliever— should engage in ordinary cultural activities such as marrying and childbearing, eating and drinking, and enforcing justice against those who disrupt the social order. The Noahic covenant itself does not tell us about the spiritual antithesis between believers and unbelievers, but this theme soon emerges again as the story of the Old Testament continues to unfold.
VanDrunen, David. Living in God’s Two Kingdoms: A Biblical Vision for Christianity and Culture (Kindle Locations 1223-1231). Crossway. Kindle Edition.