17:17 "To sanctify"(Gr. hagiazo) means to set apart for God's service (cf. Exod. 28:41; Jer. 1:5). Jesus is the perfect example of a sanctified person. He devoted Himself completely and consistently to God's will for Him. Sanctification in John's Gospel is always for a mission.526The means of the disciples' sanctification was the truth, which Jesus explained was God's Word. Jesus came to reveal God's word to humankind (1:1, 14; 14:6), and the Spirit would help His disciples understand it (15:13). It is both personal and propositional. It comes to us through the living Word of God, Jesus Christ, and the written Word of God, Scripture.
The way Jesus asked the Father to sanctify the disciples was by using His word. This means that it is essential for disciples to know, understand, believe, and obey the revelation that God has given us. The words of God that Jesus revealed and that stand recorded in the Bible are the key to believers' practical sanctification. Practical sanctification involves separation unto God from the world, the evil one who controls it, and the lies that He promotes that the world believes.
"With the mind, we learnGod's truth through the Word. With the heart, we loveGod's truth, His Son [cf. 14:6]. With the will, we yield to the Spirit [of truth, cf. 14:17; 16:13] and liveGod's truth day by day. It takes all three for a balanced experience of sanctification."527
17:18 Jesus next explained the purpose of the sanctification that He requested for His disciples. He had sent them into the world with a mission (cf. 13:20; 15:26-27; 20:21). Similarly the Father had sent the Son into the world with a mission (10:36). In both cases sanctification was essential for the success of the mission.
Comparison with verse 20 shows that in verses 6-19 Jesus was praying specifically for the Eleven. However, we should not regard what He requested for the Eleven as restricted to them exclusively. The change that takes place in verse 20 is not from one group of believers to another as though they were in separate containers. It is rather a broadening of the field from the Eleven to those that would follow them. Thus it is understandable that when Jesus prayed for the Eleven He would pray for some things that not only they but their successors would need. Clearly all subsequent believers would need sanctifying by God's Word so they could achieve their mission, as the Eleven did.
17:19 Jesus did not mean that He intended to make Himself more holy than He already was since this would have been impossible. He set Himself apart to do God's will partially for the sake of His disciples. He is our example of perfect sanctification, and His sanctification makes ours possible. Without the sacrificial death of Jesus there would be no salvation and no mission for us. There would be no sanctification for us either. One of the purposes of Jesus' death was to set believers apart to God and His mission for them to function as priests in the world.
