How long did God deal primarily with the nation of Israel?
God dealt primarily with the nation of Israel for about 2,000 years, from Abraham until Christ's first advent, with some exceptions. Even after the crucifixion, in the early chapters of Acts, Peter still addressed Israel, though the nation as a whole rejected its Messiah.
Les explains that the timeline is roughly 2,000 years from Abraham to Christ's first advent, during which God dealt only with the favored nation of Israel, with some exceptions. Even after the crucifixion, in the early chapters of Acts, Peter addressed the men of Israel and pleaded with them to respond to the fact that the one they crucified was their Messiah. But Israel nationally would not believe; some did, but for the most part the nation rejected it. So God set them aside, yet He has not turned His back on them forever. He will discipline them, and they will face the greatest discipline any people have ever had in the tribulation, but He is not destroying the nation of Israel.