Scriptures do not offer rational certitude
They offer us something much better, an entirely different way of knowing: an intimate relationship, a dark journey, a path where we must discover for ourselves that grace, love, mercy, and forgiveness are absolutely necessary for survival in an uncertain world. You only need enough clarity to know how to live without certitude! Yes, we really are saved by faith. People who live in this way never stop growing, are not easily defeated, are wise and compassionate, and frankly, are fun to live with. They have a quiet and confident joy. Infantile religion insists on certainty every step of the way and thus is not very happy.