It takes hold of what it hears and it trusts in God's Power. Faith that saves must first of all hear. We hear about the Law and Gospel that Christ preached. The Law tells us about an all-mighty God who must and will punish our sins. The Gospel tells us how he punished our sin through the death of his Son, thus giving us free salvation.
Faith hears the Law of God.
We realize that we are sinful. Death, torment and destruction all come about because of sin. Since these maladies affect each one of us, we come to recognize our sinfulness. We also hear that God wants us to be perfect, even as I the Lord your God am perfect. But we are not perfect.