Bare naked trust in Jesus' Good Friday work, not works of the Law, alone saves us. The body and blood of God's one time for all time atoning sacrifice is what faith clings to, but faith is dangerous stuff when left in the hands of sinners. The old Adam just loves to convert faith into something other than "faith in Christ's promise." He'd prefer faith be synonymous with making a decision to trust God. Faith as "I've decided to accept Jesus as my personal Lord and Savior." All so old Adam can run the verbs of salvation. But faith isn't something sinners do, let alone control. Faith in Christ's bloody suffering and death for the sin of the world is passive. Sinners are "done unto" by God. We are faithed. Put to death by God's Word of Law, we are then raised to new life by God's Word of Gospel. Sinners put to death so a new saint may arise and walk in faith in Jesus' saving work for Him.
As much as we'd prefer salvation be under our control, something we can progress through as we go from bad to good to better and, God willing, become our spiritual best, no amount of effort on our part brings us one step closer to forgiveness, life, and life eternal. Still, even when the alarms sound and we're alerted to the fact that faith is out of our control, we'd prefer to leave Jesus as Savior on the bench to spectate as we try to win the salvation game. We want to be the star of our very own drama: "Holy Moses Under The Law."
When we try to run faith, Christ becomes a new and improved Moses. This new Moses elevates the aim and goal of God's Law to a whole other level. For old Adam, faith empowers and enables him to obey God's Law (since old Adam believes that's how he earns life's rewards and life eternal from God). More than that, obedience to the Law for old Adam equals striving to fulfill God's Law, and that's ultimately God's point for sending Jesus to restore a right relationship with His creatures.
But the Bible reveals a different reality about faith. Faith isn't something we do, but something done to us by God. God's Word faiths us through the Gospel. God came down to us, we didn't climb up to Him. He is the actor, and Him alone. And when He comes, when God's Word is born in the flesh, all our illusions about using God's Law to win ourselves salvation ends.
In the early 1500s, the teaching of 'faith as a work of man' drove Martin Luther to coin the phrase, "Crux est sola nostra theologia." He wrote in all capital letters in the margins of his first Psalms lectures, "the cross alone is our theology," because he believed that's all we're given to know about God's will for us. God's judgement of our sin and death is Christ crucified. While we were still sinners Christ died for us.
God has taken all the verbs of salvation out of our hands. And that's good news for us! That means faith doesn't hang on our lawfulness or unlawfulness. Our morality or immorality, our personal holiness or unholiness don't matter a bit now. God put everything, all things, good and bad, under the title "sin" so that what was promised to faith in Jesus Christ may be given to those who believe. That's why "whatever is not faith is sin" (Gal 3:22; Rom 14:23).
All our escape routes have been cut off and blocked by God. The only way to forgiveness, life, and salvation is by way of Calvary. There is literally nothing left for us to do except enjoy Jesus' Good Friday work for us. Nothing left to do but listen to the old, old story of Jesus and His cruciform glory, because nothing, neither circumcision nor uncircumcision counts for anything anymore.
The new has come, the old is buried in a tomb twenty minutes' walk from downtown Jerusalem. All this given to us for free by God when He faiths us in Christ's promises. A bare, naked divinely inspired faith that alone saves us for Christ's sake from judgment, death, and hell. A faith that declares, "God is pleased with me, on account of Christ.”