When we hear the term “adultery” we usually think in terms of a man or woman being unfaithful to his or her spouse. But James uses the term with respect to being unfaithful to God (4:4). The Old Testament prophets referred to disobedient Israel in this way. The LORD demanded that the prophet Hosea take a harlot for a wife because Israel had committed great harlotry by departing from Him (Hos.1:2). Ezekiel called Jerusalem an adulterous wife because the people committed idolatry or spiritual adultery (Eze.16:32).
James refers to his readers as adulteresses warning them not to become friends of the world (James 4:4-6). Those who want to be friends of the world make themselves enemies of God. The world is an ordered system whose god or ruler is the devil himself. The world is characterized by the lust of the flesh, the lust of the eyes and the pride of life (1John 2:16). These things are not of God, but an affront to Him, and anyone who cozies up with or becomes conformed to this world finds himself at enmity with the Lord.
The Holy Spirit Who dwells in us is zealous for our absolute loyalty to Him, and we must always live in humility before Him (4:5-6). God resists the proud, but gives grace to the humble! May God give us the grace to remain forever faithful to Him!