But when the Helper comes, whom I will send to you from the Father, the Spirit of truth, who proceeds from the Father, he will bear witness about me. And you also will bear witness, because you have been with me from the beginning. – John 15:26-27 ESV
Once again, Jesus is attempting to prepare His disciples for His imminent departure. In a matter of hours, His betrayal and arrest will take place and the disciples will find their world turned upside down by the events that will follow. So in this message, which has come to be known as the Upper Room Discourse, Jesus gave His disciples a glimpse into what was to come, including an assurance that they would have help after He had gone. He would send them a helper or advocate, in the form of the Holy Spirit, the Spirit of truth. And according to all that Jesus said was going to happen to them after He was gone, they were going to need the Spirit's help.
First, Jesus said that the world would hate them, just as it hated Him. And they were going to be first-hand witnesses as to just how much the world hated Jesus when they saw Him brutally crucified. They would watch as the crowds turned their joyful shouts of “Hosannah!" into angry screams of “Crucify Him!” But Jesus let them know that things were going to get even worse after His departure. “I chose you out of the world, therefore the world hates you” (John 15:19 ESV). He warned them that they were going to be persecuted. Why? Because of their relationship with Him and because they were going to be His representatives on earth after He returned to His Father.
So Jesus told them to abide in Him. “I am the vine; you are the branches. Whoever abides in me and I in him, he it is that bears much fruit, for apart from me you can do nothing” (John 15:5 ESV). But this statement had to confound the disciples, because Jesus was telling them that He was going away. He was leaving them. So how were they supposed to abide in Him when He was no longer going to be with them? How was He going to be in them if He was going to be absent from them? And how could Jesus say to them, “These things I have spoken to you, that my joy may be in you, and that your joy may be full”? (John 15:11 ESV). Joy in the midst of persecution? How were they supposed to have fullness of joy at the thought of the death of their friend and teacher?
That's where the Helper was going to come in. Jesus knew something they didn't know. He knew that none of what He was asking them to do was going to be possible without help. They were incapable of surviving all that lie ahead without the aid of the Holy Spirit. The joy that would be in them would come in the form of the Holy Spirit. His presence would provide them with a constant internal reminder of all that Jesus had said and done when He was with them. The Spirit would make it possible for them to endure all the persecution that was coming and be fruitful in the process. They would not only survive, but thrive in the midst of abundant difficulty. They would discover a supernatural capacity to love selflessly and sacrificially, just as they were about to see Jesus do. The Spirit within them would bear witness to them regarding Jesus. The Holy Spirit would make sense of all the seeming madness regarding Jesus’ coming, miracles, teachings and startling death. The Spirit would provide undeniable proof of just who Jesus had claimed to be. His presence within them would prove that Jesus was still abiding with them. And as a result, they would become unwavering witnesses of Jesus, testifying of His resurrection and proclaiming His offer of forgiveness of sin and eternal life to any who would receive it.
It is the Holy Spirit who proves once and for all that Jesus was who He claimed to be and that the salvation He so boldly offered is real. The apostle Paul put it in words that make it so clear: “he [Jesus] has identified us as his own by placing the Holy Spirit in our hearts as the first installment that guarantees everything he has promised us” (2 Corinthians 1:22 NLT). In his letter to the believers in Rome, he put it this way: “The Spirit himself bears witness with our spirit that we are children of God” (Romans 8:16 ESV). It is the abiding presence of God's Spirit within us that provides us with inarguable evidence that Jesus’ offer of salvation was real. It proves that Jesus really did rise from the dead. He does sit at the right hand of the Father. He is going to return some day. The Spirit of God who lives in us is our personal guarantee regarding all that Jesus promised to us. And while we wait for the ultimate climax of all that Jesus promised: His return, we can enjoy fullness of joy and assurance of our salvation. We can experience abundant fruitfulness and express unconditional love. We can sense the reality of Christ's abiding presence and trust in the promise of His imminent return.