What does Romans 3:15 mean?

Paul moves from the mouth to the feet in his description of the sinfulness of all human beings, including both Jews and Gentiles. He has been quoting from the Old Testament to back up his statement that all people are under sin and deserving of God's anger. Feet, as used symbolically in Scripture, are representative of the intentions and actions of men. Where a person's feet go, they go; the feet are simply the mechanism by which a person "goes to" certain places. Spiritually, then, the feet symbolize the intents and behaviors of a person.

In that respect, another way we express our sinfulness is with feet that are quick to shed blood. Paul references Isaiah 59:7–8 in this and the following two verses. By nature, people are quick to hurt each other when we think it will help ourselves. Causing pain to others is a barrier we are willing and ready to cross.

James put it this way: "You desire and do not have, so you murder. You covet and cannot obtain, so you fight and quarrel" (James 4:2). This is normal human behavior, but it rightly earns for us the angry judgment of God.