"World" is one of those words with multiple meanings. It can refer to the earth, to all the people on that earth, or a philosophy or system of thought. When John says, "Do not love the world or the things in the world" (1 John 2:15), he is referring to the last of those three ideas. The behavior and philosophy of the world follows that of the prince of this world (Eph. 2:2), characterized by trespasses and sins, fleshly lusts, desires of the flesh and mind, and the like (Eph. 2:1-3). That is what we are not to love.
Paul warns against approving of those who do worldly things in Romans 1:32. Those things include all unrighteousness, sexual immorality, wickedness...evil-mindedness... inventors of evil things" and more, including homosexuality (Rom. 1:26-31). The Bible must be consulted to help determine what of the things in culture fit into the category of things like we read in Ephesians 2, Romans 1, Galatians 5, Colossians 3, 2 Timothy 3, and the like. Some things, in and of themselves, are neutral. Other things, inherently, are sinful and, thus, "worldly."
Christians set on defending, praising, promoting, or excusing things that are sexually suggestive, immodest, debauched, perverse, and depraved find themselves militating and working against the very Christ they profess to follow. To praise sin is to love the world. To defend immorality or excuse those who do it is to love the world. To see things through worldly eyes, with worldly values, is to love the world. Scripture is unequivocal about the matter. John continues, "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, the lust of the eyes, and the pride of life--is not of the Father but is of the world. And the world is passing away, and the lust of it; but he who does the will of God abides forever" (1 John 2:15b-17). Before we choose our heroes, role models, habits, hobbies, diversions, and desires, we do well to review John's God-breathed words and make sure we are not in love with the world!