There is a spectre that has long haunted Christian theology; the relationship of the material body with the immateriality of God (the Incarnation of Christ, excluded) and the immateriality of the soul/spirit, etc. However, in saying that, the problem isn’t the positing of body and soul as somehow distinct entities that cannot be reducible to each other; the distinctiveness of flesh and Spirit is a critical part of Paul’s theological understanding. Rather, the problem is in how the relationship between the material and immaterial modes of existence/reality are considered to be in relationship to each other. Christianity, particularly Western1 have long been tempted by the notion that the body and soul are separate not just in terms of substance, but in terms of functions. It is often a habitual reflex to categorize the spiritual as something that isn’t based upon one’s body or what we see, but something that is attributed to the mind or heart; i.e. thought and feelings. This tendency is most clearly and consciously expressed in the mind-body dualism of Descartes, but it has been a tendency for the Church insofar as they have been influenced by Platonism. As the Neo-Platonist St. Augustine treated the soul as a higher reality than the body, the inheritance of Western Christianity is to separate the body from the soul.
One point, among many, where this becomes a problem pertaining to Christian theology is understanding how God’s grace saves/transforms a person. If the soul, and the inner person of feeling and thoughts are what is really important for the Christian life, then what happens in the physical world and in our bodies is largely ‘immaterial’ (pun intended). This becomes most clearly expressed by the reformulation of Augustinian theology by the Reformed tradition, where nature of human free will is limited based upon the corruptness of the heart: the mechanism by which God redeems the human person so as to be free to believe, trust, and rightly worship God is by a spiritual acting upon the heart. Augustine places particular emphasis on the changing of human will in On the Letter and the Spirit and in his more polemical On Grace and Free Will. As for Calvin, following a discussion on the nature of human will and in particular the nature of the will apart from God’s grace, Calvin observes “They are sufficient, at all events, to prove the point for which I contend, t.e., that whenever God is pleased to make way for his providence, he even in external matters so turns and bends the wills of men, that whatever the freedom of their choice may be, it is still subject to the disposal of God.”2 which is then soon followed by a quote from Augustine from On Grace and Free Will. Thus within Augustinian and Reformed traditions, the internal soul/heart/spirit is treated as the point of action for God’s, whereas any action through human sensation with the outer world is not regarded as secondary.
Therefore, the tendency has been to treat mechanism of God’s action for salvation as being an inner work of the person as the paradigm of salvation. Far from simply recognizing that God’s work in a person must necessarily result in the transformation of desire that is a prevalent theme throughout the Old and New Testament, God’s mechanism of salvation necessarily entails an unmediated, interior work of the heart by the Spirit. For instance, proclaiming the story of Jesus is regarded as never being potentially sufficient to evoke faith in a person; there must always be some corollary inner redeeming of the heart by an inner work of the Spirit prior to or concurrent with proclamation. It is not sufficient to suggest that hearing about Christ’s love in his death and resurrection can move the person to faith; in other words, it is unacceptable to suggest that God may transform the heart via a mediation via one who testifies and proclaims the story of Christ. God’s saving grace entails a direct, unmediated action upon the heart by the Spirit in order to be saved.
At the end of the day, I would suggest this is a result of misreading Paul due to 1) reading the flesh-spirit duality in Paul through (Neo)Platonic lenses and 2) assuming all epistemological statements in Paul are paradigmatic for all Christians.
Regarding the flesh-spirit duality, Paul would have naturally understood flesh and spirit not as two qualitatively distinct substances that has little interaction with each other; rather he would have been influenced by Stoicism that say spirit and matter as two sides of the same coin, with spirit being the active component and matter being the passive component. While Paul’s apocalyptic perspective where God has knowledge hidden in the heavens that is not available to the earthy, material world apart from God’s action would rub up against Stoic pantheism, it is a mistake to treat Paul’s apocalypticism as suggestive of treating spirit and flesh as two separate domains that do not engage with each other in a two-way process, much as we do in the Western division of mind and body. Paul’s flesh-spirit duality is not expressing the fact that what impacts people in a physical way has no impact on the spirit of that person, nor vice-versa. It is rather the employment of the Stoic material-spirit duality but reconceptualizing it in terms of a transcendent God who sends His Spirit into the world, as if the world is not automatically in tune with the Spirit of God unless God sends Him. This does not mean, however, that the Spirit of God only works through inner work of the heart; Paul frequently makes references to the signs of wonders of the Holy Spirit 3, as if it was these dramatic witnessed events in the physical, visible world were critical to bringing people to faith; there is no mention in these instances of an inner change of heart leading to faith. This is to suggest that Paul would allow that what God does through the Holy Spirit in the physical, material world can impact the person’s inner heart to have faith; the soul/spirit of the person is not walled of from the physical realities.
Secondly, not all of Paul’s statements about epistemology are paradigmatic for all people or even for all believers. While not delving into the nitty gritty details of all of this, the best example of the problems of this assumption is the reading of 1 Corinthians. There, Paul outlines the nature of his proclamation of the Corinthians as being based upon telling the story of Christ and His crucifixion combined with a demonstration of the Spirit and power, all leading to the trusting in God’s power and not his own. Then, in vss. 6-16, Paul outlines the nature of a deeper wisdom he does teach among more mature Christians, where he places an emphasis on the Spiritual/spiritual discernment in order to accept the thoughts of God. If one notes the division between basic proclamation and maturity in 1 Corinthians 2, it would be a mistake to suggest that accepting revelation from God based upon spiritual discernment in 2:6-16 is automatically the same inner, cognitive-emotional mode of operation as the demonstration of the Spirit in 2:1-5. Rather, I would say it is exegetically necessary to treating the Spirit in 2:1-5 as entailing a physical, exterior work that impacts the person to have faith, whereas 2:6-16 is referring to an interior work of the Spirit after faith. However, if you are reading Paul’s statements as if they apply to every person or to every Christian, you will be inclined to overlook the differences between these two different epistemological stages. Therefore, because of the predominance of the Spirit being the agent of countering the desires fo the flesh throughout Paul’s letters, there is the inclination to suggest that the sole mechanism of the Holy Spirit’s work in salvation is a direct, internal changing of the mind and heart and to treat the exterior works of signs and wonders as somehow secondary and not really instrumental by itself in salvation.
In other words, the Augustinian and Reformed tradition that treats salvation as impossible prior to a direct, inner work of the Spirit is the result of an over-systematizing, Neo-platonizing, unnuanced reading of the Apostle Paul, and the Scriptures in general. In rightly noticing the absolute necessity of God’s grace for faith, the Augustinian-Reformed tradition wrongly reducing the mechanism of this grace to a direct, inner work on the mind and heart of the believer, and not allowing for a mediated change of the heart and mind through the preaching about the Word made flesh and the Spirit who produces visible signs of new creation that are witnessed by people. I would go so far as to suggest that any rejection of the effectual possibility of the Incarnation of Christ itself as an event in history and all work of the Holy Spirit, including external manifestations, that leads to necessitating yet other acts and mechanisms from God to bring people into faith and salvation represents a theology bearing some resemblance to gnosticism. By treating the physical and material as somehow inferior and ineffectual whereas thinking that it is only the internal and spiritual that is truly meaningful, Augustinian and Reformed traditions become rather Platonized.
Put differently, Western theology has been unwittingly beholden to Plato’s Allegory of the Cave by a presumptive, metaphysical separation of the world into appearances of the physical world and then the true knowledge of hidden realities. However, while Plato’s epistemology and Jewish apocalyptic epistemology share similarities in recognizing that truth is not reducible to what we normally see and know about the physical world, they share distinctly different relationships between the visible and invisible domains of existence. Jewish apocalypticism is not Platonic dualism, but we in the West have read the Bible through (Neo)Platonic.