What has God been doing for the last 1900 years?
For the last 1900 and some years, God has been calling out Gentiles to comprise the Body of Christ. This follows Israel's rejection of the Messiah, their dispersion, and the turning to the Gentile. Not exclusively, since some Jews are still being saved, but predominantly God has been calling out Gentiles.
Les explains that in the book of Acts Israel finally rejects their Messiah completely and will not have Him to be their king. God puts them into dispersion, takes away their temple, and turns to the Gentile—not exclusively, because some Jews are still being saved. But for the most part, the last 1900 and some years have been God calling out Gentiles, comprising the Body of Christ. Israel falls away, Gentiles come up, and the Church comes up, though as the book of Acts opens it has not yet reached that point.