Another argument which supports the legitimacy of Dispensationalism, even though it was formalized by John Nelson Darby in the 1800's, is that dispensations themselves were not to be revealed until the end-times. God told Isaiah (29:11), Ezekiel (28:12), and Daniel (9:24; 12:4, 9) to "seal up" the Scriptures until the end-times! I am not exactly sure how the revelation of prophecies concerning the end-times were sealed, or why, but I am sure that the writers themselves could not do the sealing: they wrote what they wrote. It is man's understanding that has been "sealed," and that is the work of the Holy Spirit. He is the Teacher of God's children, and I would suggest that He has waited until the end-times to reveal those things which were sealed (Jn. 14:26).
The Feasts of Israel teach at least four dispensations: 1) Christ's First Coming (Passover, Unleavened Bread, First Fruits); 2) the Church (Pentecost); 3) the Christ's Second Coming (Trumpets, Atonement); and 4) the Millennial Reign of Christ (Tabernacles). These clearly show that some of the prophecies concerning Christ have been literally fulfilled, and the rest will be as well.
Revelation 2 - 3 speak of the Church Age. Revelation 6 - 18 describe the Tribulation (Daniel's Seventieth Week - Dan. 9:27; The Time of Jacob's Trouble - Jer. 30:7). Revelation 20 describes the Millennium (1000 yr. reign of Christ on earth). If the Church still existed on earth during the Tribulation, why would there be a need for the Two Witnesses (Rev. 11), or the 144,000 Jewish witnesses (Rev. 7, 14)?
The Dispensation of the Church will end with the Rapture.
Read Jn. 14:1-3; 1 Cor. 15:49-54; 1 Thes. 4:13-18!