Why did the Jews at Pentecost believe Jesus was the Messiah and expect the Kingdom?
At Pentecost, Peter and the eleven preached, and many Jews believed Jesus was the Messiah and that the Kingdom was coming. Their expectation rested on the understanding that once Israel believed, the King would come; therefore they stayed in Jerusalem, sharing their goods, waiting for the imminent Kingdom.
Les explains that on the day of Pentecost and following, when Peter and the eleven were preaching, a lot of Jews believed Jesus was the Messiah and that the Kingdom was coming, because as soon as Israel had believed, the King would come. These believing Jews saw the King and Kingdom as just over the horizon, so they asked why go back to Babylon, Rome, Spain, or North Africa among pagan Gentiles when the King was coming. They stayed in Jerusalem and lived out of the common kitty as a stopgap until the King would come and the Kingdom would be set up. But Israel did not respond, the King did not come, and the kitty ran out. The people ended up poor, having sold their goods and unable to buy a ticket home. Yet God is just; they were caught in a legitimate cause because they had believed the Gospel of the Kingdom, so God would take care of them until natural death. This care came through Paul’s agreement with Peter, James, and John to remember the poor saints in Jerusalem wherever he went in his ministry.