In the Old Testament God spoke through men like Moses and confirmed his word with miracles. Today the teaching of Christ is brought to us through the Gospel delivered by the apostles on Pentecost and also confirmed by miracles (Hebrews 1:1,2; 2:3,4). In His last discourse with his apostles, Jesus promised to send through them the outpouring of the Spirit , spoken about long beforehand by prophets such as Joel, Isaiah and Ezekiel. (Matthew 26:20; John 14:25,26; 15:26,27; 16:7-13; Joel 2:28). After His resurrection He told them to wait for this promise (Luke 24:44-49; Acts 1:2-11).
This unique promise could not be realized until Christ had been glorified and had returned to the Father (John 7:39; 16:7). This outpouring of the Spirit was made available to all who call on the Lord through the inspired message taught on Pentecost by the apostles!! It was the apostles - all men of Galilee, all eleven along with Peter - who delivered the confirmed Gospel on that great day. Note that the teaching that day was done by the apostles!! (Acts 1:2-11; 2:7-15, 37,38,42,43).
After Pentecost this divine message continued to be spread and confirmed by signs done by the apostles (Mark 16:20; Acts 5:12; 6:6; 8:18; Hebrews 2:3,4; 2 Cor. 12:12). But any oral message delivered where there were no apostles present to authenticate it, needed signs for confirmation. This was done by the Spirit who gave a variety of special gifts for the purpose of confirmation, by the laying on of the apostles' hands. A careful reading of Hebrews 2:4 and 1 Cor.12:11 will show that these special gifts were given at the Spirit's direction: " according to his own will", and ..."who apportions to each ... as He wills." These gifts were not given to any who did not already have the indwelling of the Spirit that comes in obedience to Christ's baptism. Those who had only known John's baptism did not have the indwelling Spirit, and first needed the baptism taught in the Great Commission.
The Gospel confirmed by these miracles was then put in writing by the Lord's command to bring about this obedience of faith (Romans 16:25-27). Today, all who respond in loving obedience to the message of Christ crucified receive the outpouring of the Spirit, available now to people of all nations (Acts 2:38,39; 5:32; Titus 3:4-7).
This Gospel, now confirmed and written in scripture, no longer needs miracles for further confirmation. It is now God's power of salvation, it is the root of all authentic faith, and when obeyed from the heart, sets us free from sin (Rom.1:16; 10:17; John 20:31; Romans 6:3-11,17,18). This confirmed Gospel is permanent and imperishable and by it our souls are purified and we are born again (1 Peter 1:22-25).