What does it mean that faith is not the cause of salvation?

In sovereign grace theology, it is emphasized that faith is not the cause but the condition for receiving salvation. Salvation is entirely based on Christ's finished work on the cross. As stated in Galatians 2:16, 'Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.' Therefore, while faith is crucial, it is the conduit through which God's grace is applied, not an act that secures salvation.