GRACE is an invention of Catholic philosophy. Augustine was the official Catholic philosopher who defined and codified this doctrine.
Because the Catholic church was the only Christian body with official political status and power it could enforce orthodoxy by threat and banishment or worse.
When Protestantism challenged Catholicism the doctrine of Grace was re-invented. John Calvin was the re-inventor.
Augustine and Calvin were diametrically opposed, of course!
Augustine stressed "free will" and Calvin stressed predestination and the Soverign will of God in granting "grace" whimsically.
This was not the end of the matter by any means!
John Wesley (Methodism) invented Prevenient Grace as yet a third interpretation of doctrine!
Prevenient Grace is a bootstrap solution to the conflict between a wretched sinner being able to choose God in the first place--and God merely arbitrarily selecting people (outside a person's own desire) to be saved. Prevenient Grace temporaily suspends man's fallen "choice" enabling him to make a committment to Christ. Sort of like King's X.
Jehovah's Witnesses certainly get to invent their own doctrine as well!!
Jehovah's Witnesses make man free enough in his will to overcome his wretched sinful state in order to respond to Jehovah's son's offer of salvation on the CONDITIONAL basis that the undeserved "kindness" of salvation not be cancelled by failure to obey the Governing Body.
NOTE: Every single instance of GRACE is deeply flawed for three reasons.
1.All through history God has held out obedience and righteousness as the only standard possible for dealing with man. But, all men have been viewed as corrupt since Adam. Consequently, God has dealt with man on an ad hoc individual basis of eye for eye, tooth for tooth or quid pro quo.
This is God's perfect standard of Justice embodied in the law of Moses. The law of the sons of Noah (Noahide laws) apply to non-Jews.
2.God has always been just, righteous and perfectly consistent in punishing mankind UNTIL He suddenly violated His own standards in the case of JESUS. The UNdeserving are rewarded and the DESERVING is put to death. (Mankind can be regarded as "righteous" even though they ARE NOT and the perfectly righteous Jesus suffers death "as though" he were guilty of sin BUT ISN'T!
3. God is said to have "...so loved the world that he gave his only begotten son...." but no reason for loving the unrighteous is possible and no basis has ever been shown to excuse man from Adam through the Flood of Noah's day up to the destruction of Jerusalem and the coming of Jesus.
Without a logical, legal, or demonstrable basis for LOVING unrighteous sinners other than reversing his own standards, the doctrine of GRACE can only be seen as a DEUS EX MACHINA or invented plot device to explain why Jesus had to die if he were really the Messiah.
