How do we know that salvation has always been through faith?

The consistent theme of salvation by faith is evident throughout the Bible. From the very beginning, notably in Genesis 3:15, God's promise of a Savior indicates that redemption comes through faith in the promised Seed. As seen in Romans 4, Abraham was justified by faith before the law was given, illustrating that righteousness has always been obtained through believing God's promises. Thus, the gospel was foreshadowed in the Old Testament sacrificial system and has now been revealed fully in Christ. The continuity of God's plan of salvation confirms that faith has always been the means by which His elect are justified, regardless of the era in which they lived.