17 So this I say, and affirm together with the Lord, that you walk no longer just as the Gentiles also walk, in the futility of their mind, 18 being darkened in their understanding, excluded from the life of God because of the ignorance that is in them, because of the hardness of their heart; Ephesians 4:17-18 (NASB)
Genuine Christianity is that which is within the Lordship of Jesus Christ. Christians are commanded to work out their salvation with fear and trembling (Philippians 2:12) within that Lordship. We are to obey our Lord as branches abiding in the True Vine (John 15). How do we practically do this? We must work out our own salvation with fear and trembling presuppositionally, that is, with every thought, intent, and action taken captive to the will of God. We do this by approaching and living life with God at the center of all things instead of ourselves. In the passage above, (Ephesians 4:17-18) we see the opposite way to walk and the outcome of that. Unfortunately, that is how most professing believers approach this life, that is, in functional unbelief.