deterministic views (e.g., fate) of Stoics, Gnostics, and Manichaeans prevalent in the first four centuries. Christians championed the concept of a relational God who interacts with humans rather than a Stoic or Gnostic God who unilaterally foreordained every event (yet Stoics still claimed to teach free will). Patristics scholar Ken Wilson argues that every early Christian author with extant writings who wrote on the topic prior to Augustine of Hippo (412) advanced human free choice rather than a deterministic God. According to Wilson, Augustine taught traditional free choice until 412, when he reverted to his earlier Manichaean and Stoic deterministic training when battling the Pelagians. Only a few Christians accepted Augustine's view of free will until the Protestant Reformation when both Luther and Calvin embraced Augustine's deterministic teachings wholeheartedly. The Catholic Church considers Augustine's teaching to be consistent with free will. He often said that anyone can be saved if they wish. While God knows who will and will not be saved, with no possibility for the latter to be saved in their lives, this knowledge represents God's perfect knowledge of how humans will freely choose their destinies. Sociology, morals and ethics Natural law Augustine was among the earliest to examine the legitimacy of the laws of man, and attempt to define the boundaries of what laws and rights occur naturally, instead of being arbitrarily imposed by mortals. All who have wisdom and conscience, he concludes, are able to use reason to recognize the lex naturalis, natural law. Mortal law should not attempt to force people to do what is right or avoid what is wrong, but simply to remain just. Therefore "an unjust law is no law at all". People are not obligated to obey laws that are unjust, those that their conscience and reason tell them violate natural law and rights. Slavery Augustine led many clergy under his authority at Hippo to free their slaves as "pious and holy" act. He boldly wrote a letter urging the emperor to set up a new law against slave traders and was very much concerned about the sale of children. Christian emperors of his time for 25 years had permitted sale of children, not because they approved of the practice, but as a way of preventing infanticide when parents were unable to care for a child. Augustine noted that the tenant farmers in particular were driven to hire out or to