How do we know two natures doctrine is true?

The scripture teaches that believers possess two natures: one holy and righteous, which cannot sin, and the other sinful and corrupt, which is always inclined towards sin. This conflict is exemplified in Elijah’s experience. The struggle Paul describes in Romans 7, where he fights against his sinful nature, supports this doctrine. Although believers are made new and share in Christ's nature, the old nature remains and influences their thoughts and actions. This dichotomy is crucial to understanding our daily battles and the necessity of relying on grace for spiritual sustenance.