The ministry of our Lord in the Four Gospels was thus carried on, after His Ascension, by the twelve. There was no break; nor was there any new testimony beyond the fact that Christ had risen from the dead, and that they were commissioned to repeat and confirm what He had said.
To understand what their apostolic ministry (recorded in the Acts of the Apostles) was, we have only to notice what the ministry of the Lord was. We have already seen that it began, on the delivering up of John the Baptist (Matt. iv. 12), with the call to the nation to "Repent!" With the proclamation of the kingdom, and the presence of the King Who had drawn nigh (Matt. iv. 17).
We know now that the call was not regarded; and the record of the Four Gospels is to tell us how the kingdom was rejected, and the King was crucified.
The Lord did not come to found a church, but to be "a minister of the circumcision for the truth of God, to CONFIRM the promises made unto the fathers" (Rom. xv. 8); as the twelve confirmed His Word. He was not baptized to "institute" a "sacrament" for a church, but "that he should be made manifest to Israel" (John i. 31). It follows therefore, that, in the Acts of the Apostles, the twelve were not commissioned to form or found a church, but to repeat the call of Jesus Christ to repent; to confirm His proclamation as to His person; and to re-offer the King and the kingdom on the one condition of national repentance.
from pages 32- 33, Foundations of Dispensational Truth