A.T. Robertson Commentary 1 John 2:15

"Love not the world, neither the things that are in the world. If any man love the world, the love of the Father is not in him." — 1 John 2:15 (ASV)

Love not the world (μη αγαπατε τον κοσμον). Prohibition with μη and the present active imperative of αγαπαω, either stop doing it or do not have the habit of doing it. This use of κοσμος is common in John's Gospel (1:10; 17:14ff.) and appears also in 1 John 5:19. In epitome the Roman Empire represented it. See it also in Jas 4:4. It confronts every believer today.

If any man love (εαν τις αγαπα). Third-class condition with εαν and present active subjunctive of αγαπαω (same form as indicative), "if any keep on loving the world."

The love of the Father (η αγαπη του πατρος). Objective genitive, this phrase only here in N.T., with which compare "love of God" in 2:5. In antithesis to love of the world.