To discharge this function a twofold ministry is undertaken by the Spirit: He must enlighten the Apostles, and He must convince the world.
He must enlighten the Apostles. From the nature of the case much had to be left unsaid by Christ. But this would not prevent the Apostles from understanding what Christ had done, and what applications His work had to themselves and their fellow-men. "I have yet many things to say unto you, but ye cannot bear them now. Howbeit when He, the Spirit of truth, is come, He will guide you into all the truth." A great untravelled country lay before them. Their Master had led them across its border, and set their faces in the right direction; but who was to find a way for them through all its intricacies and perplexities? The Spirit of truth, He who is Himself perfect knowledge and absolute light, "will guide you"; He will go before you and show you your way.[18] There may be no sudden impartation of truth, no lifting of the mist that hangs on the horizon, no consciousness that now you have mastered all difficulties and can see your way to the end; there may be no violation of the natural and difficult processes by which men arrive at truth; the road may be slow, and sometimes there may even be an appearance of ignominious defeat by those who use swifter but more precarious means of advance; much will depend on your own patience and wakefulness and docility; but if you admit the Spirit, He will guide you into all the truth.
This promise does not involve that the Apostles, and through them all disciples, should know everything. "All the truth" is relative to the subject taught. All that they need to know regarding Christ and His work for them they will learn. All that is needed to glorify Christ, to enable men to recognise Him as the manifestation of God, will be imparted. To the truth which the Apostles learn, therefore, nothing need be added. Nothing essential has been added. Time has now been given to test this promise, and what time has shown is this--that while libraries have been written on what the Apostles thought and taught, their teaching remains as the sufficient guide into all the truth regarding Christ. Even in non-essentials it is marvellous how little has been added. Many corrections of misapprehensions of their meaning have been required, much laborious inquiry to ascertain precisely what they meant, much elaborate inference and many buildings upon their foundations; but in their teaching there remain a freshness and a living force which survive all else that has been written upon Christ and His religion.
This instruction of the Apostles by the Spirit was to recall to their minds what Christ Himself had said, and was also to show them things to come. The changed point of view introduced by the dispensation of the Spirit and the abolition of earthly hopes would cause many of the sayings of Jesus which they had disregarded and considered unintelligible to spring into high relief and ray out significance, while the future also would shape itself quite differently in their conception. And the Teacher who should superintend and inspire this altered attitude of mind is the Spirit.[19]
Not only must the Spirit enlighten the Apostles; He must also convince the world. "He shall bear witness of Me," and by His witness-bearing the testimony of the Apostles would become efficacious. They had a natural fitness to witness about Christ, "because they had been with Him from the beginning." No more trustworthy witnesses regarding what Christ had said or done or been could be called than those men with whom He had lived on terms of intimacy. No men could more certainly testify to the identity of the risen Lord. But the significance of the facts they spoke of could best be taught by the Spirit. The very fact of the Spirit's presence was the greatest evidence that the Lord had risen and was using "all power in heaven" in behalf of men. And possibly it was to this Peter referred when he said: "We are His witnesses of these things; and so is also the Holy Ghost, whom God hath given to them that obey Him." Certainly the gifts of the Holy Ghost, the power to speak with tongues or to work miracles of healing, were accepted by the primitive Church as a seal of the Apostolic word and as the appropriate evidence of the power of the risen Christ.