What does John 17:9 mean?
At the conclusion of the Last Supper (John 13—16), Jesus has been praying. These words are spoken before Jesus and the disciples cross into Gethsemane, where He will continue to pray before being arrested (Matthew 26:36–46; Mark 14:32–42; Luke 22:39–46). What we now call the "High Priestly Prayer" began with references to the glory of God (John 17:1–5). Then Christ prayed for His closest followers: the inner circle who truly believed (John 17:6–8). The "them" referred to here are those eleven men. The twelfth of that core group (Matthew 10:1–4), Judas, has already proven his lack of faith (John 17:12).Even though Jesus is most directly praying for the apostles, His prayer does have application to all who come to faith in Christ (John 17:20). The one group for whom these prayers is absolutely not applicable is unbelievers: those who do not believe in the Son of God (John 3:16–18, 36; 14:6).
Here, again, Jesus equates Himself with God the Father (John 16:15), and He will repeat that assertion in the following verse (John 17:10). Those who belong to Jesus belong to God (John 6:37).