20 “I do not pray for these alone, but also for those who will believe in Me through their word;
Jesus concluded His prayer in verses 20-26. In this section He developed the theme of the expansion of believers after His death and resurrection. He prayed for those who believed on Him during and after the time of the apostles.
There is a request by Jesus for unity among believers in verses 20-23.
20 “I do not pray for these alone,
Now Jesus shifted His intercessory prayer from the apostles to future believers at large (He 7:24-25). This was a prayer for the results of the apostles’ mission.
but also for those who will believe in Me
“Will believe” refers to future people who would “believe” in Jesus. He foresaw a time when He would “build my church” (Mt 16:18). Our Lord anticipated the fact that the apostles would have their own disciples who would form the church.
through their [the apostles] word;
“Their word” means that the future church would come to faith through communication from the apostles. These people would become believers either through the direct witness of the apostles or through the revelation to them of the New Testament.
Chapter 17 refers three times to the “word” of the Father (vv. 6, 14, 17). Now Jesus prayed about the word or message of the apostles. This message would lead to faith in Christ.
Faith comes from hearing.
Everyone who becomes a believer does so through the gospel. Unity among believers is more than a unity of love; it is unity predicated on adherence to revelation mediated through the Son (Ro 10:17).