How do we know that human efforts are in vain?

The Scriptures unequivocally declare the vanity of human endeavors. When considering our native holiness and righteousness apart from Christ, they are deemed inadequate and likened to 'filthy rags' (Isaiah 64:6). This stark portrayal serves to highlight the futility of placing confidence in oneself or in human accomplishments. Even at their best, human efforts fall short of God's glory. Thus, understanding the inherent vanity of our works directs believers toward reliance on Christ's finished work rather than personal merit.