New Defender's Study Bible Notes
17:15 from the evil. We are to be in the world, but not of the world. “The evil” is “the evil one”—that is, “the prince of this world,” Satan. Because of this prayer of Christ, no doubt, “he that is begotten of God keepeth himself, and that wicked one toucheth him not” (I John 5:18).
17:16 not of the world. We are now, because of Christ, citizens of His world, rather than this world (note Philippians 3:20). We now serve in this world as “ambassadors for Christ” (II Corinthians 5:20).
17:17 Sanctify them. The process of sanctification (that is, of being set apart from this world for His service) is accomplished through the Word of God (Ephesians 5:26), by “the Spirit and belief of the truth” (II Thessalonians 2:13).