“You believe at last!” Jesus answered.
The answer of Jesus is more a statement than a question. He is not calling the reality of their faith to question, but directing their attention to its inadequacy. They really do believe, but, as Morris observes, “they do not, as yet, know the quality of faith that stands firm in the face of difficulty and danger.” The disciples think that they now know all there is to know about that of which Jesus is speaking, but they are far lacking in their knowledge. We, too, must be careful that we don’t think that we know and understand the depths of God’s truth. His ways are higher than ours (Isa 55:8-9) and for us to think we know everything about even the smallest aspect of Christianity is at best foolish and at worst prideful.
Isaiah 55:8-9 “For my thoughts are not your thoughts, neither are your ways my ways,” declares the LORD. “As the heavens are higher than the earth, so are my ways higher than your ways and my thoughts than your thoughts.