How do we know Christ is the only righteousness we need?

The requirement for righteousness before God is insubstantial through human efforts—this is a fundamental truth within Reformed theology. We find that our righteousness can only be found in Christ, who epitomizes perfect obedience and satisfaction to God’s law. Isaiah 55 indicates that the hunger and thirst for righteousness can only be quenched through Christ, the water of life. In fact, Romans 3:10 states, "There is none righteous, no, not one;" thus, highlighting our desperate need for an outside righteousness that is provided through Jesus Christ. His death on the cross is the culmination of this need, where He fulfills the law and offers His righteousness unto us, which is credited to believers through faith.