How do we know faith is not the cause of salvation?

In understanding salvation, it is crucial to distinguish the role of faith. Ephesians 2:8-9 clearly states that faith is the gift of God, not of works, so that no one can boast. If faith were the cause of salvation, it would imply that we contribute to our own redemption, bordering on a system of salvation by works. However, the Gospel reveals that Christ alone provides salvation through His finished work. Therefore, while we are saved through faith, it is not our faith that saves us; rather, it is Christ’s perfect obedience, death, and resurrection that secures our justification before God.