Why is faith in Christ's righteousness important for Christians?

For Christians, faith in Christ’s righteousness is crucial as it is the foundation of their security before God. Isaiah 51:6 teaches that His righteousness and salvation are everlasting, meaning they do not depend on the transient works of man but on the immutable work of Christ. In Romans 10:10, we learn that with the heart one believes unto righteousness, emphasizing that faith is what unites us to Christ's completed work. This assurance allows believers to rest from their own efforts to earn salvation, knowing they are justified through faith, as God's judgment has been satisfied in His Son.