How do we know the concept of dual natures in believers is true?

The concept of dual natures in believers is grounded in Scripture, particularly illustrated in Romans chapter 7, where Paul explains the struggle between the old and new natures. After coming to faith, believers experience an ongoing battle: the flesh desires sin, while the spirit yearns for holiness. This conflict indicates that believers possess two natures within one person, shaped by their resurrection in Christ. Additionally, 1 John 5:18 states, 'Whosoever is born of God sinneth not,' indicating that while believers may still sin, their new nature—born of the Spirit—seeks to live in righteousness. John 3:6 further emphasizes this distinction: 'That which is born of the flesh is flesh; and that which is born of the Spirit is spirit.' This scriptural evidence affirms the historical Reformed view of regeneration and the necessity of being born again.