My thinking continues to grow in regards to how natural law thinking impacts our world and the Christian faith. Here is a quote from War, Peace, and Christianity: Questions and Answers from a Just-War Perspective. The first section of this book focuses on just-war tradition and the philosopher and includes a good discussion of natural law.

To the surprise of many, the notion of natural law is resolutely affirmed in the writings of the Protestant Reformers, who thought deeply about issues of government, legitimate authority, civil society, and the common good, and not merely about matters of faith, the church, and ecclesiastical culture. However deeply entrenched a present-day bias against natural-law thinking would seem to be among Protestant thinkers, it cannot be attributed to the sixteenth-century Reformers themselves. While it is undeniable that they sought to champion a particular understanding  of grace and faith that in their estimation was utterly lacking, their emphasis was not to the exclusion of modes of moral reasoning that were rooted in natural-law thinking.