Simon Peter had asked the Lord earlier on where He was going (chapter 13:36), but now that the disciples realised that He was going to leave them, their thoughts turned on themselves. They did not see their way to go on without their Teacher, and were overcome with sorrow and disappointment.
The Lord understood their feelings and immediately pointed out that, far from being harmful, it was to their advantage that He should go away. This was a startling statement, so he told them that if He did not go away, the Helper (the Holy Spirit) would not come to them. The reasons aren't mentioned here, but the following come to mind:
Christ's purpose in coming to this world was to die to give his life a ransom for many, including His disciples (Mark 10:45). When this was accomplished, He would go back to the Father because He had finished the work He was sent to do. Only after they had been cleansed of their sin by His blood, could they be baptised and sealed by the Holy Spirit.
Between the time of His birth and His resurrection, He was limited in time and space by His human body: for example, Mary and Martha said that, if He had been in Bethany (instead of Galilee) their brother would not have died. The Holy Spirit, on the other hand, is in all places: Christ said He would afterwards send Him to come and dwell in them.
The Holy Spirit had been previously at work in the world, but not in the manner in which He would operate after Christ had gone back to the Father and He had sent Him to His disciples. The Lord then explained some of the work the Holy Spirit, or Helper, would do.
When the Holy Spirit came, He would convict the world, a legal term which means the way a judge or a barrister presents evidence to bring a conviction; there must be a conviction before anybody can turn in faith and trust to Jesus Christ as their Saviour.
The conviction brought by the Holy Spirit is based on three things: sin, righteousness, and judgement:
In respect of sin: sin is defined as missing the mark and as wronging God and man. Currently some behavioural scientists and psychologists seem bent on destroying man's sense of sin, calling it merely a slip, or animal instinct, or a shortage of moral responsibility, or evil. Hence crime waves even in youth. But the Lord adds "because they do not believe in Me;" whoever rejects Jesus Christ, is, in the sight of God, the greatest sinner: he commits the unpardonable sin against the Holy Spirit. Unbelief is a state and there is no remedy for it: without this conviction by the Helper men might have a pride of intellectual superiority in refusing to believe on Jesus. Everyone who has ever heard the gospel is responsible for his decision concerning Jesus Christ.
And of righteousness: the Lord Jesus was delivered for our offences: He died on the Cross in our place, taking on Himself the guilt for our offences, and was raised again for our justification (Romans 4:25). He was raised from the dead so that we might not only have our sins subtracted, but so that we might have His righteousness added: we need righteousness if we are to have any standing before God (Philippians 3:8-9). He returned to the Father because He had completed His work of redemption, and would no longer be seen by His disciples. With the bodily eyes and without the Holy Spirit they were unable to behold Christ with the spiritual vision (John 14:19).
And of judgement, because the ruler of this world is judged: the prince of this world, Satan, has already been judged, so we live in a judged world "For the wages of sin is death; but the gift of God is eternal life through Jesus Christ our Lord" (Romans. 6:23). The world is like the man waiting in death row for his execution: he doesn't like to hear about judgement, and resents it a great deal. The lost world hates many things about God: for instance, His omnipotence: they don't like the fact that it is His universe and He is running it His way. They don't like the fact that God saves by grace and that man has already been declared lost.
The disciples had to gradually learn the things of God - they could not be imparted by Christ all at once, and the Holy Spirit would continue to teach them after the Lord had returned to the Father.
Seven prophetic steps are mentioned here:
The Holy Spirit, the Spirit of Truth, was to come;
He would then guide them into all truth;
He would not speak from Himself;
He would speak whatsoever He hears;
He would tell them things to come;
He would glorify the Lord Jesus Christ; and
He would take of what was Christ's and declare it to them.
The whole of this prophecy was fulfilled during the time of the apostles, from the day of Pentecost until John received the last prophecy on the island of Patmos, the Revelation of the Lord Jesus Christ.
The Spirit of God came at Pentecost, and He guided them in all truth both in their preaching and in their writing, and we find it in the Epistles and the Book of Revelation. The ministry of the Holy Spirit was to complete the teaching of the Lord Jesus Christ. The books of the New Testament are the unfolding of the person and ministry of Christ, they glorify Christ and show Him as the Head of the church, and they speak of things to come as well as of His coming again to establish His Kingdom.
Like the disciples, we don't know all truth at the beginning either, but we are personally to keep growing in grace and in the knowledge of our Saviour. The Holy Spirit must be our Teacher as we read the Bible inspired by Him, and He will lead and guide us into all truth.
The Lord Jesus made it very clear that the Holy Spirit would not speak of Himself, but would glorify Christ. One need only refer to Peter's sermon at Pentecost after the coming of the Holy Spirit, to Peter's Epistles, to Paul's Epistles, to Hebrews, to John's Epistles, to see how under the tutelage of the Holy Spirit the disciples grew into the fullness of the knowledge of God in the face of Christ (2 Corinthians 4:6).
This provides a good test of what we hear and read. We must beware of so-called Holy Spirit revivals, working of the Holy Spirit, and the Holy Spirit doing this and that, for the Holy Spirit is not working unless Christ is being glorified. We do see Him working when, for example, in a meeting or a Bible study we get a glimpse of the Lord Jesus and He becomes wonderful, very real, and meaningful to us.
Again the Lord Jesus made Himself equal with God. Whatever the Father had, Jesus had. "He will take of Mine and declare it to you" means He will take the things of God and show them unto us. Only He can do that. "Eye has not seen, nor ear heard, nor have entered into the heart of man the things which God has prepared for those who love Him, but God has revealed them to us through His Spirit. For the Spirit searches all things, yes, the deep things of God." (1 Corinthians 2:9,10). The Spirit is the One who searches the deep things of God and He alone can show these things to us.
5 "But now I go away to Him who sent Me, and none of you asks Me, 'Where are You going?'
6 "But because I have said these things to you, sorrow has filled your heart.
7 "Nevertheless I tell you the truth. It is to your advantage that I go away; for if I do not go away, the Helper will not come to you; but if I depart, I will send Him to you.
8 "And when He has come, He will convict the world of sin, and of righteousness, and of judgement:
9 "of sin, because they do not believe in Me;
10 "of righteousness, because I go to My Father and you see Me no more;
11 "of judgement, because the ruler of this world is judged.
12 "I still have many things to say to you, but you cannot bear them now.
13 "However, when He, the Spirit of truth, has come, He will guide you into all truth; for He will not speak on His own authority, but whatever He hears He will speak; and He will tell you things to come.
14 "He will glorify Me, for He will take of what is Mine and declare it to you.
15 "All things that the Father has are Mine. Therefore I said that He will take of Mine and declare it to you.