How do we know faith in Jesus is essential for salvation?

The Scriptures teach that faith is vital for salvation, as articulated in Ephesians 2:8-9: 'For by grace are you saved through faith; and that not of yourselves: it is the gift of God: not of works, lest any man should boast.' This emphasizes that salvation is a divine gift, not earned through human effort. In the case of the leper who returned to thank Jesus, his faith was acknowledged as the means that brought him spiritual wholeness, demonstrating the necessity of trusting in Christ as Savior.