Pelagianism argues that man is naturally able to obey God. Semi-Pelagianism argues that though man cannot be saved apart from grace he is naturally able to turn to God. It’s quite frustrating when Arminianism and Molinism are equated with Pelagianism. It seems as though those who make these arguments fall short of fully knowing the two positions and play the P-card as a the trump card. To briefly state the differences, Pelagianism isn’t even close to Arminianism and Molinism and if you play that card you need to stop before your get to the bulb of the TULIP or ROSES and go back to the soil and seed. Semi-Pelagianism can’t be dismissed off the bat like that though. The difference is that prevenient grace is what enables the will to turn to God as a catalyst. If semi-Pelagianism is true, theoretically, I could be wanting salvation from God and he not give it to me. If Pelagianism is true I can will myself to God and salvation. For the Arminian and Molinist, neither of these are true; rather, the sinner rejects God and salvation prior to being overcome by God’s ever-present prevenient grace catalyzing the will and God saving.
The teaching of Scripture seems to assert that post-Genesis 3 humans possess libertarian free will, including freedom to choose between opposites on matters pertaining to salvation or any other spiritual good. This immediately raises questions surrounding the concept of original sin. Augustine first used the expression “original sin” in the wake of the Pelagian controversy. Upon arriving at Rome in A.D. 400, the British monk Pelagius was horrified to see the open immorality prevalent among so-called Christians. This was the direct result of Theodosius I nineteen years earlier (A.D. 381) declaring Christianity to be the state religion so decreeing that anyone living within its borders to be Christian. This was a transformation of Christianity from a voluntary religion (one that people freely choose to join) to a natural religion (one into which people are born) spawned immense immorality in many people who bore the name of Christ without ever having personally committed their lives to Jesus. Pelagius exhorted the Romans to live worthy of their Christian calling with an argument logically summarized in two steps:
1. Humans possess libertarian free will.
2. Humans should use their libertarian freedom to be good enough people to earn their own salvation.
Unfortunately, as so often happens in the history of thought, one extreme position meets the response of an equally extreme opposing position, thus swinging the ideological pendulum from one side to the other. Very rarely is prudence taken in shifting the pendulum back to the center, where the truth is most likely to be found. Augustine affirmed that both Adam and Eve were created with libertarian free will pre-Genesis 3 whereby one could freely respond to the grace of God. However, in response to Pelagius, Augustine was not content merely to reject Pelagius’ conclusion but insisted on preventing the argument from getting off the ground. Denying both Pelagian premises, therefore, Augustine asserted that post-Genesis humans lacked libertarian free will and so could not use this ability to earn salvation. Augustine proposed an innovative interpretation of Genesis 3, henceforth styled “the Fall,” according to which Adam and Eve, in the supreme act of self-violation, paradoxically committed “spiritual suicide” by freely employing their mental faculty whereby they could freely respond to God to destroy that very faculty.
If grammatico-historical exegesis is performed upon each of the pertinent Scriptural passages rather than theological eisogesis, it quickly becomes apparent that post-Genesis 3 unregenerate humans in fact possess the freedom to choose between opposites including response to grace, which is precisely what the late-Augustinian doctrine of original sin denies. As for Genesis 3, nothing in the text even remotely suggests that humans surrendered the libertarian freedom with which they were created.
When Paul asserts that unregenerate humanity is spiritually dead or dead “in transgressions and sins” (Eph. 2.1), he means that their spirits are alienated from Divine Spirit and thereby relegated to lives of pointlessness; this is why Paul interchanges phrases connoting spiritual death with such descriptive phrases as “separate from Christ,” “without hope and without God in the world” (2.12), “living in the futility of their thinking” (3.17), and “darkened in their understanding and separated from the life of God” (3.18). Granting in grammatico-historical fashion of the sense of literary context as well as the normal connotations of and relationships between terms, it follows that any text where God offers people a choice requires that people have the mental faculty necessary for making that choice. Denying this inference not only makes the text meaningless, but it carries the deleterious theological consequences of either invalidating God’s omniscience (for wrongly thinking people could make the impossible choice) or God’s veracity (for intentionally deceiving people into thinking they could make a choice which He knew they lacked the ability to make and for inspiring a Scripture which foisted the ruse upon its readers).
 Augustine, De Gratia Christi, et de Peccato Originali, contra Pelagium, First Series, ed. Philip Schaff. (Christian Literature Publishing Company, 1887; rep. ed., Peabody, MA: Hendrickson, 1994), 2.1-5.
 Pelagius, Commentary on St. Paul’s Epistle to the Romans, trans. Theodore de Bruyn (Oxford: Oxford University Press, 1995), 107.
 Earle E. Cairns, Christianity Through the Centuries, 3rd rev. ed. (Grand Rapids, MI: Zondervan, 1996), 120-121.
 Pelagius, Commentary on St. Paul’s Epistle to the Romans, 108-112. It should be noted that the second premise is entirely unbiblical. Anselm in his Cur Deus Homo, 1.20-23, 2.6, decisively overturned this inference. Accordingly, it is beyond the power of any person to make compensation for his or her sin by right employment of libertarian freedom.
 Kirk R. MacGregor, A Molinist-Anabaptist Systematic Theology, (Lanham, MD: University Press of America, 2007), 22.
 Augustine, De Peccatorum Meritis et Remissione, 2.
 Augustine, De Gratia et Libero Arbitrio, 29-30.
 Augustine, De Peccatorum Meritis et Remissione, 5-16.
 MacGregor, A Molinist-Anabaptist Systematic Theology, 24. For further exegetical and grammatical relationships see William W. Klein, Craig L. Blomberg, and Robert L. Hubbard, Jr., Introduction to Biblical Interpretation, (Dallas, TX: Word, 1993), 155-214.
 Irenaeus, in Against Heresies, 4.37.2-3, averred in the face of Gnostic determinism that the prophetic rebukes for spiritual evil and exhortation of spiritual good presupposed human ability to obey, as did the religious teachings of Jesus. Hence both Old and New Testaments substantiated the self-determination of humanity. By libertarian freedom I mean that our freedom is a derived freedom, humans are not completely independent or completely autonomous. In Molinism, unlike Calvinism, God is completely sovereign over the eternal destinies of a world of libertarian free creatures who have, in Augustinian terminology, “free choice” and not merely “free will.” MacGregor explains that for Augustine, “free choice” (i.e. libertarian free will) entailed the freedom to choose between opposites in both the physical and spiritual realms. Thus fallen humanity, by virtue of the imago Dei, can freely choose whether or not to respond to God’s prevenient grace. By contrast, Augustine defined “free will” (i.e. compatibilist free will) as the ability to choose without any external constraint between the options compatible with one’s nature. On this view, unregenerate humans, due to original sin, lack the ability to choose between spiritual good and evil. Just as a bad tree can bear bad fruit or no fruit at all, unregenerate humanity can either perform spiritual wickedness by actively rebelling against God or do nothing spiritual at all by displaying passivity toward God. See Augustine, On Forgiveness of Sins and Baptism, in Nicene and Post-Nicene Fathers, First Series, ed. Philip Schaff (Christian Literature Publishing Company, 1887; rep. ed., Peabody, MA: Hendrickson, 1994), 5:57-59, 74-76. MacGregor, A Molinist-Anabaptist Systematic Theology, 84-85. The Scriptures breathe libertarian human freedom, even if the Bible makes no explicit mention of it. Take, for example, 1 Cor. 10.13, which promises that God “will not allow you to be tempted beyond what you are able, but with the temptation will provide the way of escape also, that you may be able to endure it.” It follows that any Christian who does not in some circumstance endure but succumbs to temptation had it within his power to take the way of escape instead, i.e., he had the liberty of opposites in those circumstances. Again, we can at least agree that if the Scriptures do presuppose or affirm libertarian freedom, then there is no basis for denying that sentences like 1 Cor. 2.8 are true counterfactuals of freedom. William Lane Craig, “Ducking Friendly Fire: Davison on the Grounding Objection.” Philosophia Christi 8 (2006): 166.
 MacGregor, A Molinist-Anabaptist Systematic Theology, 26.