What does the Bible say about inward wickedness?

In Mark 7:21-23, Jesus reveals that it is from within the heart of man that evil thoughts, adulteries, fornications, and all manner of sinful behavior proceed. This reflects the biblical understanding that the human heart is corrupt and unable to produce genuine righteousness on its own. It highlights our need for an internal transformation and cleansing that only God can provide. The problem lies not in external influences but in our nature, which needs redemption and the work of the Spirit to transform our hearts and align them with God's will.