What does James 4:1 mean?

Chapter and verse divisions were not part of the original texts of the Bible. These breaks were added many centuries later in order to make it easier to refer to specific passages. Therefore, even though this verse begins a new chapter, James is continuing a single train of thought from chapter 3 where he just compared the results of living by the wisdom of heaven, versus the results of living by the world's wisdom.

The world's wisdom states that human beings are responsible to identify what they want out of life and to make a plan to get it at all costs. This has become such a "normal" perspective that even Christians may see nothing abnormal about it. It even sounds industrious to most of us. The problem with this attitude is that it puts the focus of our lives on ourselves. Success, according to the world, is defined by whether we get what we want out of life. Worldliness is driven by envy—"I want that"—and selfish ambition—"I will do whatever it takes to get that."

James 3:15–16 noted that this un-heavenly wisdom is earthly, unspiritual, and demonic, leading to disorder and all kinds of evil practices. Now he scolds his readers, who, though they are Christians, are continuing to live by the world's warped wisdom. Apparently, the community that James was writing to was in conflict. He rhetorically asks what is causing their fights and quarrels. They likely would have been tempted to answer that question by pointing to their opponents. James won't let them get away with that. Instead, using another question, he says their conflict is driven by the passions or desires that are battling within them.

Just like unbelievers, these Christians had decided they were not willing to give up getting what they wanted. They were not willing to trust God to provide good for them (James 1:7) in His time. Driven by envy and selfish ambition, they wanted to win.