2 Chronicles 29:6, "For our fathers have trespassed, and done that which was evil in the eyes of the LORD our God, and have forsaken him, and have turned away their faces from the habitation of the LORD, and turned their backs."
The word "trespassed" in the verse translates to an act of treachery; an act of faithlessness. The people were faithless; they didn't believe. They were unbelieving of the law which God had given them to live by. They fell victim to the world and all manner of pagan worship.