How do we know that salvation is through faith in Christ alone?

The doctrine of salvation through faith in Christ alone is rooted in the understanding that faith itself is a gift of God. In Ephesians 2:8-9, it clearly states that 'by grace are you saved through faith; and that not of yourselves: it is the gift of God.' This reflects the Reformed position that no human effort can achieve salvation; it is entirely dependent on God’s sovereign grace. Furthermore, the gospel preached both in the Old and New Testament emphasizes reliance on Christ’s finished work rather than our own merits, thus reinforcing that we are justified by faith alone.