“…in whom there is no guile”.
Homing in on the simpler reality shows the Diabolos, or serpentine activity of the mind, the creator of guile (trickery); seemingly “passive”in Nathanael about whom this comment was made. It could simply have been Jesus commenting on Jewish shrewdness in business, and maybe Nathanael was an exception to this possibly common trait in Jews.
But maybe it ran a little deeper than this, Nathanael seemed a devout man and it may have reflected on an unusually “good” heart. It is said that “Out of the heart comes evil etc…” See Matt 15-18,19,20. Mark 7-21. Luke 6-45. Prov 4-23.
If the heart is “cleansed by faith” then, it is this evil that is cleansed, in terms of both its residue and its origin. Out of the cleansed heart then comes the good things of God.
This is why it was said that the heart is deceitfully wicked above all things. “But their hearts were cleansed by faith”. It is the cleansing of this heart that then allows God to dwell therein.
The heart then is cleansed by faith in Jesus, his death and resurrection. This consequently means that the evil source, the “diabolos” and his guile, are “abolished”, just as both the law and death are said to be abolished.
All of this “abolishment” comes from and by faith, because we “believe”. Abraham believed and it was “credited” to him as righteousness. Other versions say “reckoned” and “imputed”. This means that his internalisation of the structural things of God was causing a reality of righteousness to be present in his thinking. (or “heart”).
The righteousness imparted to us by faith in Jesus is superior to any other kind of structural impartation. Once this impartation was to be by law, but simple structural representation of God and his righteousness was insufficient to cover the dynamic of sin.
Faith in Jesus is faith in the power of God’s love to overcome all obstacles to keeping us from that love, and which is accessible by faith in his love, by faith in his already demonstrated love in Christ crucified and risen.
Faith in death having been totally dealt with empowers us by his Spirit to overcome all that opposes his reign of life.