"If I Go Not Away"
It was necessary for the Lord Jesus Christ to go away. He must be lifted up upon the tree, He must suffer and die. He must rise from the dead, ascend back into heaven and appear in the presence of God for us. Otherwise, we could never have been saved. The purpose of God, the Word of God, the promises of God and the covenant of grace would all have been defeated and proven a lie. This is what our Savior meant when he said, "It is expedient for you that I go away."
Had Christ not gone away the Holy Spirit would never have come in his office capacity as the Comforter of his people, Reprover of the world, Teacher of truth and Glorifier of Christ. There would have been nothing for him to do! Had Christ not gone away, there would have been no blood to sprinkle, no righteousness to reveal, no salvation to bestow, no Mediator to glorify.
Without question, the Holy Spirit was in the world from the beginning (Gen. 1:2; Psa. 51:11). Without him the prophets could not have prophesied and the Old Testament saints could not have been saved. But he was not poured out upon all flesh (the Gentile world), for the gathering of God's elect from the four corners of the earth, until Christ died and ascended back to heaven. This coming of the Holy Spirit was the direct result of Christ's exaltation and glory as our Savior (Gal.3:13-14;John 7:39;Psa.68:18;Joel 2:32; Acts 2:33).
In the infinitely wise and orderly arrangements of the covenant of grace all the blessings of the covenant were conditioned upon one thing. And that one thing was the obedience of Christ as the Surety of God's elect, his righteousness and blood atonement. As God the Holy Spirit is the Conveyor of all grace, he would not come to convey to us the blessings of grace promised in the covenant until our Surety had earned and purchased them for us. The sending of the Spirit was to be the fruit of Christ's purchase. Therefore he could not come until the purchase was made. But, inasmuch as Christ has by his blood purchased God's elect from under the curse of the law and purchased for them all the blessings of the covenant, the Spirit of God will and must come to every redeemed sinner in irresistible, saving power. He comes to seal to us all that the Father promised and the Son purchased by giving us life and faith in Christ and preserving us in grace until the resurrection day.