Justification by faith according to Paul is the state of being acquitted and accepted by God. Paul believed that humans cannot attain righteousness by their own efforts, but rather through faith in Jesus Christ. Therefore, justification by faith means that one is declared righteous by God, not because of their own actions, but because of their faith in Jesus Christ. This faith leads to acceptance and reconciliation with God, and the person is no longer condemned for their sins but considered righteous through Christ.