Ephesians 4: 17-19 (KJV) reads: "This I say therefore, and testify in the Lord, that ye henceforth walk not as other Gentiles walk, in the vanity of their mind, Having the understanding darkened, being alienated from the life of God through the ignorance that is in them, because of the blindness of their heart: Who being past feeling have given themselves over unto lasciviousness, to work all uncleanness with greediness."

In this passage, the Apostle Paul is addressing the Ephesians, urging them to live a life that is separate from the world and to not conform to the ways of the Gentiles. He warns against walking in the vanity of their minds, having their understanding darkened, and being alienated from the life of God due to their ignorance and blindness of heart. Furthermore, Paul criticizes the Gentiles for giving themselves over to lasciviousness, indulging in uncleanness with greediness, and being past feeling.

One of the key themes of this passage is the call to live a holy and righteous life that is separate from the ways of the world. Paul is exhorting the Ephesians to be transformed in their thinking and behavior, and to live in a manner that is pleasing to God. This call to holiness is a recurring theme throughout the New Testament, as believers are called to be in the world but not of the world, and to pursue a life of righteousness and godliness.

The context of this passage is important to understanding its message. Paul is writing to the Ephesian church, which was located in a city known for its idolatry and immorality. The Ephesians were surrounded by a culture that embraced sinful behaviors and pagan practices, and Paul is urging them to reject these influences and to pursue a life that is centered on Christ. The passage serves as a warning to the Ephesians to guard against being swayed by the prevailing culture and to remain true to their faith.

Symbolism can also be found in this passage, particularly in the contrast between walking in the vanity of the mind and walking in the light of God. The vanity of the mind represents a life devoid of spiritual truth and wisdom, filled with empty pursuits and worldly desires. In contrast, walking in the light of God symbolizes a life that is grounded in truth, righteousness, and obedience to God's word. The darkness of the understanding and the blindness of the heart also serve as symbols of spiritual ignorance and the need for divine enlightenment and revelation.

Ultimately, this passage serves as a powerful reminder for believers to be mindful of the influences around them and to strive for holiness in their daily lives. It emphasizes the importance of renewing the mind, seeking after the knowledge and truth of God, and living in a manner that reflects the character of Christ. The message of Ephesians 4: 17-19 is as relevant today as it was in the time of the Ephesian church, and it continues to challenge believers to live in a way that honors God and stands apart from the world.