In John 17:6-8, Jesus says, "I have manifested your name to the people whom you gave me out of the world. Yours they were, and you gave them to me, and they have kept your word. Now they know that everything that you have given me is from you. For I have given them the words that you gave me, and they have received them and have come to know in truth that I came from you; and they have believed that you sent me."
The disciples constantly misunderstood Jesus. By this time, they were sure they finally understood what He had come to accomplish.
John 16:31-32 says, "Do you now believe? Behold, the hour is coming, indeed it has come, when you will be scattered, each to his own home, and will leave me alone."
Jesus knew they didn't yet understand what had to take place. But doesn't His prayer in verses 6-8 of John 17 sound as if He's pleased with them?
True, they had stuck with Him through difficult times. When thousands turned away because of difficult teachings. Even when Jesus's life—and theirs—was in danger.
But were they not stubborn, selfish, arrogant? Did they not lack insight and understanding?
Jesus isn't ignoring these truths and pretending His disciples don't have issues. Instead, He is expressing how far they've come despite those issues.
In John 11 we read that Jesus and the disciples fled Jerusalem because Jesus had said He was one with the Father and the authorities were seeking to kill Him. But when Lazarus died, Jesus returned to the region.
Knowing they could be killed, what did the disciples do? In John 11:16, Thomas "said to his fellow disciples, 'Let us also go, that we may die with him.'"
Jesus was not oblivious to their many weaknesses. But He acknowledged—even though they struggled, even though they sinned, even though they doubted, even though they don't understand, and even though they would desert him—they had kept His word. They knew the Father because of Him. They knew He had come from the Father. And they believed the Father had sent Him.
Marcus Rainsford, a pastor in Ireland back in the 1800s, when thinking through this verse, wrote:
"Let us evermore remember this most precious fact, that however in His wondrous grace our blessed Teacher may [show us] our deficiencies; however He may correct and rebuke us, [showing] us in our daily experience how needy, how feeble we are, and of how little faith—yet our standing before God is in the fullness of our Head and Representative; and He will never allow us to appear before His Father otherwise than as endued with all the completeness of His own righteousness." 
Christ also knows our flaws—each one of them.
But we can rest in the truth of Colossians 1:22, "He has now reconciled in his body of flesh by his death, in order to present you holy and blameless and above reproach before him."
Still, we must be careful not to live as unbelievers live. We are to reflect Christ to those around us (Ephesians 4:1). To effectively do so, we must grow increasingly close to the Lord. From our perspective, this journey began the moment we believed in Christ as our Lord and Savior, but it didn't end there. As we dig into the Scriptures, we are molded into His image.
First John 2:3 says, "And by this we know that we have come to know him, if we keep his commandments."
God uses people who know Christ and keep His Word. Jesus goes one step further. We must strive for holiness and unity.
In John 17:11-12, Jesus says, "And I am no longer in the world, but they are in the world, and I am coming to you. Holy Father, keep them in your name, which you have given me, that they may be one, even as we are one. While I was with them, I kept them in your name, which you have given me. I have guarded them, and not one of them has been lost except the son of destruction, that the Scripture might be fulfilled."
As believers, we must strive for holiness and unity. The only way we're able to do this is by dying to self, which is one of the hardest things we can do. But that's what God calls us to.
Paul says, in 2 Corinthians 7:1, "Since we have these promises, beloved, let us cleanse ourselves from every defilement of body and spirit, bringing holiness to completion in the fear of God."
In order to reach the world for Christ, the Father uses His people, those who pursue holiness. Part of that process is striving for unity. The process of truly dying to self includes how we interact with one another. Doing so in a God-honoring way can be incredibly challenging.
In Ephesians 4, Paul commands us to preserve unity, to fight for it, to go above and beyond to maintain it.
In Matthew 5:9, Jesus says, "Blessed are the peacemakers, for they will be called children of God."
If we're not striving for holiness, if we're not striving for unity, we must ask ourselves if we're truly children of God. Even if we are genuine believers, our determination will ebb and flow. We won't always get it right.
But if continue to study God's Word, He will reveal those areas in which we are not yet victorious over sin. He will give us the determination and the wherewithal to repent and walk in increasing obedience. We will die to self, not just individually but also corporately. We will move toward holiness and unity.
And something amazing will happen more and more. God will use us to reach the world with the gospel, which is truly awesome!
 Our Lord Prays for His Own: Thoughts on John 17, p. 129