"Sin is one of those concepts that, on first glance, would seem to need no explanation. What is more central to the Christian faith than the understanding that all have sinned and fallen short of the glory of God? Sin is, in short, the reason we need a Savior to rescue our relationship with our Creator.
Like all powerful words, however, "sin" carries layers and subtleties of meaning that require further explanation. "Sin" commonly refers to willful acts of disobedience but can also refer to corporate or systemic moral transgression, to a pervasive part of humanity's condition that leaves us estranged from God, and to a state of falleness into which we are born.
"Sin" can also refer broadly to the distortion of all of God's creation from what God intended it to be. Cornelius Plantinga notes that the word sin encompasses everything that violates God's shalom, the peaceful and just harmony that he intended for his creation. Christ followers, then, are to be shalom restorers."
- From "Sin" in the Dictionary of Christian Spirituality.