At the same time the Spirit who would come from God the Father was to witness on behalf of Christ. But a little thought will soon reveal what a source of conflict and division this notion of two different witnesses can bring about. Two witnesses to the truth can easily become, within the wide range of fallible human experience, two authorities which differ on what the truth may be. There has always been a struggle in the church to hear what the Spirit is saying while receiving also the witness of the apostles. It is not at all uncommon for people to say that God has given them a personal word of advice, that they have discerned in prayer, meditation, conversation or sudden revelation, what they should do or believe.
Some people live that way from day to day.
And, after all, do not all believers in God pray at times for personal guidance, and are we not told to listen as well as talk in prayer. Many a time such a personal word is believed to be the work of the Spirit of God guiding us as Jesus had promised the Spirit would. Both the Spirit and the apostles were, of course, present on the Day of Pentecost. The apostles were the core of the group who received the Holy Spirit in the great outpouring on what we call the birthday of the church. They were the representative spokesmen of the group.