How do we know the doctrine of justification is true?

Justification is a central theme in Paul's letter to the Galatians, where he clarifies that it is by faith in Jesus Christ that believers are justified and not by works of the law (Galatians 2:16). This doctrine finds its roots in the Old Testament as well, notably in Genesis 15:6, where Abraham's faith was counted as righteousness. The consistent biblical testimony affirms that justification is a gracious act of God, who declares sinners righteous based solely on their faith in Christ's finished work, demonstrating the profound nature of God's grace and the security that believers have in their standing before Him.