What was Israel's spiritual state at the end of the 40 years?
At the end of the 40 years, Israel remained adamant in unbelief. The period from the crucifixion to the temple’s destruction was a time of testing, yet the nation did not repent. Consequently, God permitted Rome to destroy Jerusalem and the temple and sent Israel into dispersion among the nations.
Les explains that the book of Acts covers a 40-year period in which God was still dealing with His covenant people, even though He was beginning to go to the Gentiles before that 40 years ended. In Israel’s history, 40 years has always been a period of testing, and at the end of that testing, Israel is still adamant in their unbelief. A valid offer had been made: every Jew had to repent and follow with water baptism, and then Christ would have ushered in the tribulation, lifted the curse, and brought in the kingdom. But God knew Israel would not do it, and He knew He would go to the Gentiles without Israel. So at the end of the 40 years, because of Israel’s continued unbelief, God permitted Rome to come in, destroy the city in an awful siege, destroy the temple, and send Israel into dispersion among all the nations.