Why can’t we be justified by our works?

The inability to be justified by works is foundational in Reformed theology. Romans 3:20 highlights that no flesh will be justified by the deeds of the law, as all have sinned and fall short of the glory of God. The law, while good and just, merely reveals our sinfulness and guilt. Any attempt to justify oneself before God through personal righteousness is doomed to failure since all our righteousnesses are as filthy rags, unable to satisfy God's demand for perfection. Thus, justification rests solely in Christ's finished work on our behalf.