What were the Jews in Jesus' earthly ministry supposed to believe about Him?
The Jews were to believe He was the Christ, coming in fulfillment of the Old Testament covenant promises. At that time Christ had not yet died, and they had no idea He was going to die. His earthly ministry was directed primarily to Israel, who required a sign.
Les teaches that the signs in John are not just miracles or wonders but signs, because the Jew required a sign. All eight signs are directed to the nation of Israel. Everything in Christ's earthly ministry was directed primarily, not exclusively, to the Jew under the covenant promises of the Old Testament. Christ had not yet died, and the Jews had no idea He was going to die. They were to believe He was the Christ coming in fulfillment of those Old Testament covenants. Every Jew Jesus dealt with was still a law-keeping Jew, and the Temple was still going full blast.