Adulterers and adulteresses! Do you not know that friendship with the world is enmity with God? Whoever therefore wants to be a friend of the world makes himself an enemy of God.

James 4:4

What emerges from the epistle is a portrait of Christian readers many of whom are materialistic in outlook, cultivating connections with the wealthy while pursuing financial success for themselves. But all of this was worldly to the core. Did his readers not realize, James asks, that friendship with the world is enmity with God? Did they not know that whoever … wants to be a friend of the world makes himself an enemy of God?

Often in the NT the term world (kosmos) is used of a system or entity that is hostile to God and is manipulated by Satan (e.g., 1 Cor 1:20–21; 2:12; Gal 6:14; 2 Pet 1:4; 1 John 2:15–17; 3:1; 5:19). Materialism, immorality, and spiritual blindness are all components of this wicked entity and are in sharp conflict with God’s interests and purposes on earth. James is insistent here (as is John in 1 John 2:15–17) that one cannot be on good terms with both God and the world. One must choose the side he is really on, and when one opts for friendship with the world, he automatically opts for enmity with God. He has chosen the status of an antagonist toward his Maker and Redeemer. This is just like when a married man decides to engage in immorality with a woman to whom he is not married. In that very decision he chooses to reject fidelity to his wife. Thus in their craving for worldly acceptance and standing, James’s Christian readers are committing spiritual adultery and renouncing friendship with their Lord. It may have surprised many of them to hear it put this way, but James’s aim is to wake them up to the sad depth to which their spirituality and devotion had sunk.

Zane C. Hodges, “The Epistle of James,” in The Grace New Testament Commentary.