What does the Bible say about the cause of sin?

Judges 5:8 identifies the root cause of Israel's sin as the choice to serve new gods. This reflects the fundamental issue of humanity, where mankind repeatedly chooses to rebel against God's commands. From the fall of Adam, this tendency to choose self over God has been the source of all sin. James 1:14-15 explains that we sin when we are drawn away by our own desires, and that choice ultimately leads to death. Thus, our natural inclination toward sin stems from our will, which, apart from the regenerating work of God's grace, is free only to pursue sin.