What caused the change in the Old Testament program?
The change occurred when Israel rejected the King and the Kingdom. Jesus was then crucified and returned to heaven, not immediately coming after the Tribulation. Instead, God set Israel aside for about 2,000 years while the Church Age unfolded, a mystery not revealed in the Old Testament.
Les teaches that the Old Testament program anticipated Israel having the King and the Kingdom, after which Israel could carry the knowledge of salvation to the Gentiles. But that program changed when Israel rejected the King and the Kingdom. Jesus was crucified and went back to heaven, not to immediately come after the Tribulation. Now there is a 2,000-year wait while Israel has been set aside and the Church Age has been operating. This was not revealed in the Old Testament; it is part of the secret God had not yet given.