The following is an excerpt from The MacArthur New Testament Commentary on 1 John 2.

Do not love the world nor the things in the world. If anyone loves the world, the love of the Father is not in him. For all that is in the world, the lust of the flesh and the lust of the eyes and the boastful pride of life, is not from the Father, but is from the world. The world is passing away, and also its lusts; but the one who does the will of God lives forever. (1 John 2:15-17)

The kingdom of the world and the kingdom of God are inherently incompatible (cf. 4:5–6; 5:4–5; John 15:19; Gal. 6:14). The two are mutually exclusive and opposed to one another. They are antithetical, and cannot peacefully coexist. True Christians therefore will not be characterized by a habitual love for the world, nor will worldly people demonstrate a genuine affection for the gospel and its Lord (John 3:20; Acts 7:51; 13:8–10; 17:5, 13; Rom. 8:7; Col. 1:21; 1 Thess. 2:14–16).

Clearly, there is an unmistakable line of demarcation between the things of God and the things of the world. The ongoing moral and ethical deterioration of contemporary culture makes this obvious. Even brief consideration provides a lengthy list of cultural agendas that are aggressively hostile to biblical Christianity: an attack on the traditional family by feminism; an active promotion of sexual promiscuity and homosexuality; an increasing acceptance of violence; an emphasis on materialism and hedonism by the secular media; a steady decline in standards of personal integrity and business ethics; an undermining of right and wrong by postmodern relativism; and so on.

In order to support his admonition, John does not offer a long list of specifics or detailed illustrations. Instead, he presents general reasons believers must not love the world: because of who they are, because of what the world does, and because of where the world is going.

Because believers are forgiven (Pss. 86:5; 130:3–4; Isa. 1:18; Matt. 26:28; Luke 1:77; Eph. 1:7; 4:32; Col. 1:14; 2:13–14; 3:13; 1 John 2:12), have a true knowledge of God (2 Cor. 2:14; 4:6; Eph. 4:13; Col. 1:9–10), have the Word of God abiding in them (Ps. 119:11; Col. 3:16), have overcome Satan (James 4:7; 1 John 4:4), and have an increasingly intimate relationship with the Father (1 John 2:12–14), they cannot love the world. Anyone who loves the world demonstrates that the love of the Father is not in him. Like Demas, such spiritual defectors manifest that any previous claim to know and love God was nothing but a lie (2:19).

Nonetheless, the basic identity of believers as God’s children does not make them immune to the world’s allure. Because they are still fallen sinners—though saved by grace—true followers of Christ are tempted through their remaining flesh by the world’s behaviors and enterprises (Matt. 26:41; 1 Cor. 10:13; Gal. 6:1; Eph. 6:16; James 1:12–14; 1 Peter 5:8–9). Whether the temptation comes from worldly priorities, worldly amusements, worldly riches, or worldly lusts, believers desire to resist the world’s effort to seduce them. As Jesus warned His listeners, “No servant can serve two masters; for either he will hate the one and love the other, or else he will be devoted to one and despise the other. You cannot serve God and wealth” (Luke 16:13; cf. Matt. 6:19–21, 24).