What Jesus says in this 6th chapter of John is almost the flip side of the Priscilla's story. You may think you know what it is to love Jesus, and follow him, but you don't. Not until you are drawn by God into his world of life and light, and you spend a lifetime eating his flesh and drinking his blood, and going where you've never gone before. Eugene Lowry talks about two kinds of knowledge. And you agonize for hours and hours before the answer finds its way into your consciousness.
Faith definitely falls in the second category.