John 15:22 "If I had not come and spoken to them, they would have no sin, but now they have no excuse for their sin."
Our Lord Jesus taught the Jews that He was the Son of God and Messiah, Who came as the sacrificial Lamb of God and not as a King
Luke 1:76 “And you, child, will be is called the prophet of the Highest; for you will go before the face of the Lord to prepare His ways, to give knowledge of salvation to His people by the remission of their sins,
Zechariah prophesied John the Baptist ministry and the birth of the soon coming Messiah. So before our Lord Jesus began His ministry, God ensured that all the religious leaders knew that the coming Messiah would give them salvation by the remission of their sins. They refused to accept Him as the Lamb of God and crucified Him.
Luke 2:11,17-18 For there is born to you this day in the city of David a Savior, who is Christ the Lord... Now when they had seen Him, they made widely known the saying which was told them concerning this Child. And all those who heard it marveled at those things which were told them by the shepherds.
Six months later, they heard the shepherds proclaiming that the Messiah was born in the stable in Bethlehem as announced by the angels.
Mat 2:4-5 And when he had gathered all the chief priests and scribes of the people together, he inquired of them where the Christ was to be born. So they said to him, “In Bethlehem of Judea,"
Not long after that the priesthood and scribes were summoned by Herod, who demanded them to show the visiting wise men (magi) the birth place of the Messiah. So once again, the religious leader were told of the birth of the Messiah.
John 1:29 The next day John saw Jesus coming toward him, and said, “Behold! The Lamb of God who takes away the sin of the world!
John the Baptist pointed to Jesus the Messiah, reminding them that He would come as the sacrificial Lamb of God (for the Jews were expecting Him to come as the King of Israel)
John 6:32-33 Then Jesus said to them, “Most assuredly, I say to you, Moses did not give you the bread from heaven, but My Father gives you the true bread from heaven. For the bread of God is He who comes down from heaven and gives life to the world.”
Our Lord Jesus is the Word, which is our spiritual food (true bread from heaven) and by abiding to it, we will find eternal life.
Mat 20:18-19 “Behold, we are going up to Jerusalem, and the Son of Man will be betrayed to the chief priests and to the scribes; and they will condemn Him to death, and deliver Him to the Gentiles to mock and to scourge and to crucify. And the third day He will rise again.”
Again and again our Lord Jesus told them that He would come as the Lamb of God, Who will cleanse them of their sins by replacing their imperfect animal sacrifices.
Heb 9:13-14 For if the blood of bulls and goats and the ashes of a heifer, sprinkling the unclean, sanctifies for the purifying of the flesh, how much more shall the blood of Christ, who through the eternal Spirit offered Himself without spot to God, cleanse your conscience from dead works to serve the living God?
Mal 4:5 Behold, I will send you Elijah the prophet (John the Baptist) before the coming of the great and dreadful day of the Lord.
The great and dreadful day was upon the Jews the moment they rejected and crucified our Lord Jesus. Since then Jews are no longer the people of God.
Brethren, Jews are no longer the people of God and their salvation is only in our Lord Jesus.