The bible uses "the world" in various ways. Barnes in his commentary wrote, "The term [world] seems to be used in the Scriptures in three senses;
(1,) As denoting the physical universe; the world as it appears to the eye; the world considered as the work of God, as a material creation.
(2.) The world as applied to the people that reside in it — " the world of mankind."
(3.) As the dwellers on the earth are by nature without religion, and act under a set of maxims, aims, and principles that have reference only to this life, the term comes to be used with reference to that community; that is, to the objects which [they] peculiarly seek, and the principles by which they are actuated, Considered with reference to the first sense of the word, it is not improper to love the world as the work of God, and as illustrating his perfections; for we may suppose that God loves his own works, and it is not wrong that we should find pleasure in their contemplation. Considered with reference to the second sense of the word, it is not wrong to love the people of the world with a love of benevolence, and to have attachment to our kindred and friends who constitute a part of it, though they are not Christians. It is only with reference to the word as used in the third sense that the command here can be understood to be applicable, or that the love of the world is forbidden; with reference to the objects sought, the maxims that prevail, the principles that reign in that community that lives for this world as contradistinguished from the world to come. The meaning is, that we are not to fix our affections on worldly objects — on what the world can furnish — as our portion, with the spirit with which they do who live only for this world, regardless of the life to come. We are not to make this world the object of our chief affection; we are not to be influenced by the maxims and feelings which prevail among those who do. "
I would agree with Barnes that it is the third meaning that is meant when John writes that Christians are not to love the world.
To add to this. A lot of this has to do with the nuances and various uses of the Greek word
kosmos.
In its most basic sense the word
kosmos simply means "order" or "an arrangement". A common mythological motif in the ancient world, and this is true of the Greeks and their neighbors, is the concept of order arising from an un-ordered emptiness. The Greek term for this un-ordered emptiness is
chaos. The exact way(s) in which order arises from chaos depends on the culture(s) telling their creation stories. Even the Bible has its own version of this in Genesis chapter 1, we read that the earth was a formless waste with the primordial waters (a common way of talking about chaos in the ancient world); God takes the world and over the course of six days, or refains of "evening and morning" order and form is given to the unordered and formless world.
So it isn't hard for the word
kosmos to get used to describe what we might call "the natural order", aka the universe or world in the sense of all the stuff we see--the land, the plants, the animals, mountains, rivers, oceans, the sun, moon, and stars.
Many of the pre-Socratic philosophers were interested in digging deeper into this idea of kosmos, and so we see all sorts of questions arise about what is kosmos, and how it works. Heraclitus and Parmenides for example. But then we also get Pythagoras and his more mystical approach with numbers, and the Stoics and their ideas. Eventually we get Socrates, Plato, and Aristotle and "classic" Greek philosophy.
So kosmos can mean the natural order or "the world" in the sense of nature, the natural things we see. But it also can get deeper into questions like the forces and powers that operate, the ordering principle. And not just the ordering principle of nature, but the ordering principles of human beings and their societies, governments, and inter-personal relationships.
By the time of the New Testament is written, kosmos is a complex word that encompasses a lot of ideas depending on context. Which is why we can see the use of the word kosmos used in different ways throughout the writings of the New Testament. In the New Testament we see how the Greek idea of the Logos as the ordering principle of the kosmos is used, and appropriated as talking about Christ, such as in the first chapter of the Gospel of John, but it's found throughout the New Testament in its Christological statements, such as in St. Paul's epistle to the Colossians, or in the anonymous epistle to the Hebrews.
God as the creator of the universe is the Lord and Maker of the kosmos, and God rules the kosmos through His Logos (which is Christ). Since God made all things, and human beings are beloved of God, He loves human beings, therefore "God so loved the world that He gave His only-begotten Son", this is God's love of His creation, yes; but more than that, it is the specific love God demonstrates toward what we might term "the human world"; out of which God joins and participates in through the Incarnation, God become human and part of the human story and the history of humanity.
But there is also something else going on, there is something wrong in the good creation--there's death, there's injustice, people who are supposed to reflect the Divine image and likeness instead do all kinds of messed up things--they aren't doing as they should. They are "missing the mark" and erring--which is what "sin" means. The story of this goes all the way back to the biblical story of Adam and Even in the Garden, and is viewed as the constant problem of how the world now operates. The systems of order in the world are, in a sense, broken, there's something wrong with them. The New Testament uses terms like "powers and principalities" to talk about how the structures of how the world operates has something wrong with it. This problem exists not only in the broad structures of how things work--there is suffering and death, but also the ways humans organize themselves often involves violence and suffering, from oppression (such as Rome's oppressive ruling over the Jews, itself would be seen as a pattern of foreign powers conquering and oppressing, Assyria, Babylon, Macedonia, the Seluecids, and now Rome), to corrupt magistrates, the abuses of power. But also including all inter-personal relational dynamics--unfaithfulness of spouses, murder, envy, being deceitful, using people for selfish gain, the list goes on. So that the problem is not just what we'd call systemic, it's personal--the problem runs through the middle of each of us; and it is found at every level of how our lives are ordered and structured. In ourselves, in our relationships with other people, and in our larger human relationship with the broader world.
It's this sense of kosmos that is condemned as bad; the sinful, violent, broken, system of how things are where death, sin, and injustice seems to rule the day.
The New Testament contrasts this with what Jesus offers, which is a different sort of kingdom, a different sort of ordering, and ultimately a different sort of world--one rooted not in death, but resurrection. Something literal that will happen in the future, a world in which men beat their swords into plowshares, and even the lion eats straw like an ox and a small child can play near a viper's den without fear of harm, a world where justice flows like an uninterupted stream, a world where God is exerienced in such a way that His presence covers the whole earth the same way water covers the oceans. And according to the New Testament, this world can be experienced, in part, right now--proleptically in the life of faith.
Presumably, a person who really does believe in something like this would, even though quite imperfectly, have an affect on how they view things and their views shaped by this kind of belief. They would, for example, even if they struggle with it, recognize their own failure to cultivate a behavior of love, and a love of peace, and a love of justice as something that should change, and involve the continued changing of their thoughts and attitudes, what we would call "repentance" which isn't just "oh oops, I goofed" but actually refers to this Greek word
metanoia, literally "changing of one's mind". Thus a distinction could be made between the person who takes these things seriously, and the person who--say--just likes marking "Christian" on a checklist without any real care or concern about what that is supposed to mean in any real way.
-CryptoLutheran