Knowledge and faith go together
We don’t have to look very far into our own thinking and living to see the effects of either being sure of God or not being sure of God. I believe that scripture always presents real faith as something that is based on knowledge as well as something that goes beyond anything you could know, and involves a commitment to God and his kingdom. Those two things, knowledge and commitment, are not exclusive of one another; rather, they are related. If we do not have a knowledge of God at the foundation of our commitment, that commitment simply will not hold up. It will waver; it will not govern our lives. It will be like pulling a chair away from someone in the act of sitting down. We will not be able to hold on to our belief as God intends, by the action of his Spirit on our hearts and our minds.
Knowledge and faith are intended to go together. For example, when you read Hebrews 11, the great chapter on faith, you will see faith equated with a vision of reality. We are told that Moses endured as one who sees the invisible. Faith is not a mere thought that something is true or the hope or resolve to believe it is. As Martin Luther said in the preface to his commentary on Romans:
Faith is a living, well-founded confidence in the grace of God, so perfectly certain that it would die a thousand times rather than surrender its conviction. Such confidence and personal knowledge of divine grace makes its possessor joyful, bold, and full of warm affection toward God and all created things—all of which the Holy Spirit works in faith. Hence, such a man becomes without constraint willing and eager to do good to everyone, to serve everyone, to suffer all manner of ills, in order to please and to glorify God, who has shown toward him such grace. It is thus impossible to separate works from faith—yea, just as impossible as to separate burning and shining from fire.
From The Allure of Gentleness: Defending the Faith in the Manner of Jesus. Copyright © 2015 by Dallas Willard. All rights reserved. Used with permission of HarperCollins Publishers.