I always thought it amazing that Christ says, “I tell you the truth: it is to your advantage that I go away.“ 
How could it ever be advantageous for Christ to leave the disciples? Christ is God manifested to the world. Why would it be good for humanity that Christ leave? In His grace, Jesus gives us the answer…“for if I do not go away, the Helper will not come to you. But if I go, I will send him to you.” The Helper is the Holy Spirit that is sent by the Son from the Father, and He has a particular purpose. “And when he [Holy Spirit] comes, he will convict the world concerning sin and righteousness and judgment: concerning sin, because they do not believe in me; concerning righteousness, because I go to the Father, and you will see me no longer; concerning judgment, because the ruler of this world is judged.”

Concerning Sin

Concerning SIN – The Holy Spirit will show us our true state – SINFUL. He will convict the world because they refuse to believe that Christ is the Son of God, the Messiah – the sin that damns people to Hell. The question we raised in John 2 comes back again – “Who is Jesus to you?” The Holy Spirit is the One who opens the eyes of the world to answer this question rightly. If He is your Savior and Lord, you will have life. If Christ is anything else, you will receive death and punishment. 

Righteousness

Concerning RIGHTEOUSNESS – The Spirit will not only convict the world of their sin but will show them the righteousness of Christ, “because I go to the Father, and you will see me no longer.” Jesus goes to the Father and is accepted by Him because He is the only One who is righteous. Showing the world their sin would be of no value if there were not an answer. But after showing us our depravity, the Holy Spirit reveals the glory of Christ to the sinful world. Because of the Spirit’s work, we can be dressed in the righteous robes of Christ. Remember in Revelation, the saints look like the Christ. The reason – we are children of the King. We bear His mark and because of His righteousness, we can be saved!

Judgment

Concerning JUDGMENT – Plainly, the Holy Spirit convicts the world showing that the ruler of this world is already judged. If we follow him, we too will be judged with him. Why join the team who has already lost?

The Holy Spirit is sent after Christ leaves and convictS the world. He will imprint the message and words of Christ onto the hearts of men. The Holy Spirit will be our Guide. He will be our Comfort. He will dwell IN US! He will SEAL us forever to the Father. As the Holy Spirit comes, Christ ascends to be with the Father and will petition the Father on our behalf. Christ will become our great High Priest! Because of Christ, we have a place before the Father!

If Christ would not have ascended, the world would not be awakened by the Holy Spirit to the glory of the Gospel!