It is significant that they do not say that now they completely understand what He has been saying. Instead they say that they understand that He knows all things. They have full confidence in Him. The basis for this expression of faith is that He answered their questions without them having to ask (16:19).

John 16:19  Jesus saw that they wanted to ask him about this, so he said to them, “Are you asking one another what I meant when I said, ‘In a little while you will see me no more, and then after a little while you will see me’?

Even though they are now starting to find some faith and expess this confession, it is really quite inadequate in the light of what they have seen and heard. Westcott observes that, “This common confession of faith shows how little even yet the disciples had apprehended the nature of Christ. As a body they had not advanced as far as the Baptist.” and Lightfoot notes that “a belief resting on the ground of His knowledge was found at the outset in Nathanael (1:47-50) and in the Samaritan woman (4:29); and a faith which has now seen greater things than these (1:50) should have a deeper basis.”

John 1:47-50  When Jesus saw Nathanael approaching, he said of him, “Here is a true Israelite, in whom there is nothing false.”  “How do you know me?” Nathanael asked. Jesus answered, “I saw you while you were still under the fig-tree before Philip called you.”  Then Nathanael declared, “Rabbi, you are the Son of God; you are the King of Israel.”  Jesus said, “You believe because I told you I saw you under the fig-tree. You shall see greater things than that.”

John 4:29  “Come, see a man who told me everything I ever did. Could this be the Christ?”

John 1:50  Jesus said, “You believe because I told you I saw you under the fig-tree. You shall see greater things than that.”

However, we should not overlook the fact that their words close with an expression of trust.

What helps them to understand what Jesus is saying is the observance of what must be omniscience on His part in discerning what they were talking about and in revealing to them what their real needs were. How many time over the past 3 years had He told them that He came from God and they now finally believe? And how often have we expressed faith in Him and what He will do for us and yet when we experience His power and His intervention for us, our faith goes up a notch or two?

In James it says that faith without works is dead (James 2:26). It is speaking of our works following our faith, but it could also be said that faith without God’s works will die. Abraham, the man of faith, waited for years for God to keep His promise of a son and then decided to take matters into his own hands because his faith wavered. The faith of the disciples crashed at the cross but came roaring back to life much greater than it had ever been with their view of the resurrected Christ. One of the reasons that God allows bad circumstances into our lives is that they turn abstract faith into a burning reality in our lives when He does come through for us. Though faith based on works alone is not real faith, man has a need in him to see the result of his faith or it will eventually wilt and die like an unwatered plant. One of the ways to water the plant of faith is to constantly remember the times God has proven Himself to us. God taught us that principle when He had the Israelites set up the 12 stones on the shore of the Jordan river after He stopped up the waters so they could cross (Joshua 4:1-7).

James 2:26  As the body without the spirit is dead, so faith without deeds is dead.

Joshua 4:1-7  When the whole nation had finished crossing the Jordan, the LORD said to Joshua,  “Choose twelve men from among the people, one from each tribe,  and tell them to take up twelve stones from the middle of the Jordan from right where the priests stood and to carry them over with you and put them down at the place where you stay tonight.”  So Joshua called together the twelve men he had appointed from the Israelites, one from each tribe,  and said to them, “Go over before the ark of the LORD your God into the middle of the Jordan. Each of you is to take up a stone on his shoulder, according to the number of the tribes of the Israelites,  to serve as a sign among you. In the future, when your children ask you, ‘What do these stones mean?’  tell them that the flow of the Jordan was cut off before the ark of the covenant of the LORD. When it crossed the Jordan, the waters of the Jordan were cut off. These stones are to be a memorial to the people of Israel for ever.”