Unsurprisingly, David's argument contains shallow and frankly hollow criticisms of which the following is a typical example:
An example of such a flawed, Gnostic-tinged theology is Augustine's idea of predestination, that God had elected from eternity to save some while condemning the rest to damnation. Anyone familiar with Gnostic theology can see the influence of the Gnostic belief in the saved pneumatikoi versus the damned somatikoi.This and the other argument employ filtering (aka confirmation bias) and treat any similarity no matter how superficial as evidence of influence. It is the same fallacy employed by Dan Barker in his debate with Dr. White in suggesting that mythology had some influence on the gospel accounts (catch a portion of that debate here).
There may be some similarity between the pneumatikoi and the spiritual (πνεύματος - pneumatos in Romans 8:6) and the somatikoi and the carnal (σαρκὸς - sarkos in Romans 8:6) such that the body (σῶμα - soma in Romans 8:10) is dead because of sin but the Spirit (πνεῦμα - pneuma in Romans 8:10) is life because of Christ. There may be some similarities, and it may even be that one is derived from the other. But the bare fact of some similarities (particular superficial similarities like the similarity between the fatalistic aspects to certain forms of Gnosticism and the predestination of Scripture/Augustinianism/Calvinism does not prove that one was derived from other.