How do we know that only faith in Christ leads to salvation?

The sermon emphasizes the exclusivity of salvation through faith in Christ, as articulated in Isaiah 45:22. It is asserted that no other gods or means can save; only the just God and Savior can achieve this. The sermon also draws parallels with Christ's teaching, where He claims in John 14:6 that He is 'the way, the truth, and the life.' This unity of the message throughout scripture supports the doctrine that salvation is granted solely through faith in Christ, negating any other method or mixed works.