Some dispensationalists believe so strongly in dispensationalism that they will tell you the exact time and date that God closed the door of the ark, or when He chose Abraham. Others vary on the number of dispensations throughout the Bible. Some say there are four, while others, like myself, believe there are seven. Regardless of what the "experts" say, one thing is clear by studying the Church Age: the change from one to the next is not always so clear. It is almost universally believed among Christians that the Church began on the Day of Pentecost the year Christ arose from the grave. I agree, but did the Apostles understand it?
Jesus told His disciples to wait in Jerusalem until they received the Holy Spirit. And, one would assume that when Pentecost came with the manifestation of the Spirit and the salvation of three thousand, they would know the Church Age had begun. But this is not the case. In fact, as far as I can tell, they believed that they were Messianic Jews. They did not believe that they were starting a separate religion, but that they were to continue the work of Jesus and transform Judaism. They worshiped and preached in the Temple until the resistance became persecution. In Acts 5:40, they were physically beaten for their preaching of the Gospel, and yet they continued teaching daily in the Temple. The first death for preaching Jesus didn't occur until the end of Acts Seven. By this time, the Apostles had been trying to convert the thinking of the Jews for at least three years. Following the stoning of Stephen, the disciples, with the exception of the Apostles, scattered (Acts 8:1).
Jesus had told His disciples that they were to preach the Gospel in Jerusalem, Judea, Samaria, and to the uttermost parts of the world (Acts 1:8). The transformation from being a Jewish Sect to being Christians occurred slowly. It required severe persecution by the Jews in order for God to get the Church to leave Jerusalem. Peter was told by Jesus that he was to determine who was to be allowed in and who was to be kept out (Matthew 16:16-19). In Acts 8:14-17, Peter was sent to verify that Samaritans had been saved. In Acts 10:1-48, Peter learns that God intended the Gentiles to be included. It wasn't until Chapter Eleven that the new sect of Judaism was first recognized as being as separate group known as Christians (v. 26). In Acts Fifteen, the Apostles came to the conclusion that the Gentiles did not have to become Jews in order to be recognized as members of Church. It had taken about sixteen years for the Apostles to get the message: the Church is not merely a part of Judaism, but it is part of a new stewardship of God's light.
Lord willing, I will continue on the subject of the evolving Church tomorrow. As you will see, it required several Church Councils to get everyone on the "same page." It wasn't until the 1500's that the Church was successfully challenged concerning the many false doctrines that had crept into its teachings.