Question:
I remember one question I asked when I was being raised, but keep in mind this was a child's question in a grown up world at the time.  I could never understand why if Christ died on the cross, as "the king of jews," why there was a separation between Jews and Christians, why they sected off, and did not stay just Jewish.  Now that I am older, I understand, but I think many Muslims don't understand this part of Christianity.  It would be good to explain this point.

Answer:
Thank you for your question. The simple answer is that there are many Jews who rejected Jesus as the Messiah and King.

Jesus said he was the Christ or Messiah. Christ is the Greek term and Messiah the Hebrew. Both mean "the anointed one." In Israel , anointing was the way you were initiated into office. The king, prophet and priest were all anointed. In Israel this anointing was done at God’s command and the person anointed became the Lord's anointed. So King David was the Lord's anointed. But the prophets predicted the Messiah or anointed one would come (unlike all the other anointed ones that were present all the time) and that was what Israel was waiting for. However at the time of Jesus, most of the Jews were looking for a Messiah or Christ who would be a military king and would use the sword to defeat their enemies and subdue the idolaters. You can see this expectation because after Jesus, around the year 132, a man named Bar-Kokhba arose and claimed to be the Christ. The Jewish nation followed him in a war against the Romans that resulted in the deaths of hundreds of thousands and the scattering of the Jews. But if they would have looked closer at the prophets they would have realized that the Christ was to be a prophet, priest and king but he would not set up an earthly kingdom. In the prophet Zechariah ( 9:10 ) it says, "Rejoice greatly, O Daughter of Zion (Zion in the Bible is a name for Jerusalem)! Shout, Daughter of Jerusalem! See, your king comes to you, righteous and having salvation, gentle and riding on a donkey, on a colt, the foal of a donkey." Jesus was a king having salvation, not riding on a warhorse to destroy the enemies. In the Injil the book of John 12:12 -19 it says, "On the next day the large crowd that had come to the Passover festival heard that Jesus was coming to Jerusalem. So they took palm branches and went to meet him. They were shouting, "Hosanna! Blessed is the one who comes in the name of the Lord, the king of Israel!"

Jesus obtained a donkey and sat on it, as Scripture says: "Don't be afraid, people of Zion! Your king is coming. He is riding on a donkey's colt."

At first Jesus' disciples didn't know what these prophecies meant. However, when Jesus was glorified, the disciples remembered that these prophecies had been written about him. The disciples remembered that they had taken part in fulfilling the prophecies.

The people who had been with Jesus when he called Lazarus from the tomb and brought him back to life reported what they had seen. Because the crowd heard that Jesus had performed this miracle, they came to meet him.

The Pharisees said to each other, "This is getting us nowhere. Look! The whole world is following him!"

The crowds welcomed him as a king but didn't see his true purpose. So one reason Jesus was rejected was because he wasn't the kind of Messiah the people wanted. They didn't want salvation from sin or from the wrong they did but from the Romans. Isaiah 53:3 predicts the rejection of Jesus by many. But while the leadership rejected Jesus not all the Jews rejected God's Messiah.

One thing many people don't realize is that all the early Christians were Jews. One modern Jewish man who became a Christian was shocked when he read the New Testament because it was all about Jews. So at the time of Jesus, and even the first 50 to a hundred years after, the Christian church was mainly made up of Jews or led by Jews. And to the present day there have always been Jewish Christians who recognize that Jesus is the Messiah.

So, back to the simple answer. The separation came because the majority of the Jewish people rejected Jesus as the Christ or Messiah.