Exhortation to Righteous Living (4:17-32).
‘This I say therefore, and testify in the Lord, that you no longer walk as the Gentiles also walk, in the futility of their mind. Being darkened in their understanding, alienated from the life of God because of the ignorance that is in them, because of the hardening of their heart.
The fact that they are intended to grow into a full-grown man involves their lives being in total contrast to those of others, especially their fellow-Gentiles. They are to no longer walk as they walk. What the state of the Gentiles in general is, is then laid out. Their mind is vain, their understanding is darkened, their hearts are hardened. Thus they are alienated from the life of God.
‘In the vanity of their mind.' The mind here is mainly the moral thought and attitude combined with the spiritual thought (compare ‘the mind of the flesh' (Romans 8:6), the mind controlled by the flesh). In men generally this is ‘vain, empty, purposeless'. The word mataiotes means ‘emptiness, futility, purposelessness, transitoriness'. It is going nowhere and has no end in view. Such men's lives are futile.
‘Being darkened in their understanding.' They are lost in the dark, and their minds are in darkness. Things always look different in the dark so that what in the light would be seen as tawdry and unacceptable, in darkness seems acceptable. This was the condition of the Gentiles. But it is not because they could not know. It is because they ‘hold down the truth in unrighteousness' and refuse to accept God's light through nature. It is because ‘they became vain in their reasonings and their ‘senseless heart was darkened' (Romans 1:18-21). Thus they turn away from the light of the world and walk in darkness and do not know where they are going (see John 12:35; John 8:12; 1 John 1:6).
‘Alienated from the life of God because of the ignorance that is in them because of the hardening of their hearts.' It is hardened hearts, not ignorance, that is their real problem. They close their minds to the truth about God because they do not want to face up to His demands. They prefer the desires of the flesh. Thus they have no part in life from God. They are totally separated from Him and completely alienated. And this despite the fact that many were ‘very religious'. But their religion was not a light, it was only darkness. Their thoughts were futile, their minds were in darkness, they were alienated from God. What a dreadful condition they were, and are, in.
Notice the two sides to their condition. Their minds are darkened, by the god of this world ‘lest the light of the good news of the glory of Christ shine on them' (2 Corinthians 4:4), and they are alienated from the life of God, and thus strangers to Him.
‘Hardening.' Porosis, ‘obstinacy, dullness, insensibility'.