Unity among His disciples is the focus of the High Priestly Prayer of Jesus when He prays for those who will believe in Him on account of the Apostolic testimony (John 17:20–26). When Christians live in unity with one another, the world will know that Jesus has been sent by God and is the supreme revelation of God. Such unity, of course, cannot come at the expense of the truth. After all, Jesus also prays that His people will be sanctified “in the truth,” namely, the truth of God’s Word (v. 17). There can be no true unity that dispenses with doctrinal unity, no true unity that treats essential matters of the faith as indifferent things.
We see the importance of unity grounded in the truth again in today’s passage, where Jesus speaks of His giving His disciples the glory the Father has given to Him. This glory is given for the purpose of our unity (v. 22). What Jesus means by “glory” in this verse is debated, but it is not difficult to understand what our Savior refers to when we look at “glory” in the context of John’s gospel and the rest of Scripture. Importantly, John 1:14 speaks also of the glory given to Christ by the Father that He then has given to His people, and in context John is speaking of our Lord’s revelation of God to His people. He is speaking of our Savior’s revelatory act in showing and proclaiming the truth of God to us. This fits in well with what Scripture says elsewhere about God’s glory. For example, Numbers 14:22 makes reference to the Israelites who saw God’s glory in Egypt. They saw God reveal Himself as the true and mighty Savior as He conquered Pharaoh and His army in the plagues and the exodus (Ex. 7–14). To see God’s glory is to see God for who He is, to understand the truth about our Creator and His character.
Thus, when Jesus says He has shown His glory to His disciples for the purpose of their unity, He is really saying that He has revealed the truth of God to them for the sake of their oneness (John 17:22). Christian unity, therefore, must be grounded in truth, particularly the truth of God as He has revealed Himself in Christ.
When such unity occurs, Jesus says the world will know that God has loved His people just as He has loved His Son (v. 23). This verse tells us, incredibly, that the Father loves us with the same perfect, eternal love with which He loves the Son. If we are in Christ, God cannot stop loving us, for He cannot stop loving His Son. We are secure in His grace forever, for His love for us cannot end.