Acts 1:4-11; John 16:7
Why did Jesus have to leave?
Jesus told the disciples to go to Galilee. It was on a mountain there that he gave them the Great Commission. Then he told them to go to Jerusalem. In Jerusalem, he told them to wait for the gift, the power. He gave them additional information regarding their mission, that they will start in Jerusalem, then go to Judea, to Samaria, and finally to the ends of the earth. Ten days before the Jewish Feast of Pentecost, he ascended to heaven leaving the disciples.
Why? If he had come to proclaim the Kingdom of God, why did he have to leave. He said he had to leave so He could send the Advocate (the Holy Spirit). It was for a special reason.