How do we know that we need a new heart according to the Bible?

In Ezekiel 36:26, God promises to give His people a new heart, indicating that the old heart—one of stone—cannot fulfill God's commands or live righteously. The need for a new heart is reinforced by the realization that our natural state is dead in sin (Ephesians 2:1). The transformation from a heart of stone to a heart of flesh symbolizes a complete renewal that allows believers to walk in God's ways and be obedient to Him. This prophecy is fulfilled through the work of Christ, who alone can give us the heart we need to be in a right relationship with God.