Those who wanted to kill Jesus did so for one main reason: They didn't want to hand over the control of their lives to Him. To put it another way, they realized that if Jesus was the Son of God (as He claimed), then they couldn't keep on living the way they wanted to.
Think, for example, of King Herod. When the wise men came to Jerusalem they asked one question: Where can we find the new king of the Jews? When Herod heard this, he was enraged; he had no intention of giving up any of his power. As a result, he made a determined effort to have the young child killed, forcing His family to flee to Egypt. (You can read about this in Matthew 2.)
Herod soon died—but throughout Jesus' ministry, some people felt threatened by His claim to be the Son of God and were determined to kill Him. In spite of His miracles and His teaching, they refused to believe in Him. They knew that if they did, they'd have to change their way of living and become His followers. They refused—and eventually they urged Pilate to condemn Him.
Although we live in a different world, the human heart has not changed. We want to run our own lives, and we don't want to hand control over to Jesus. Like the people in one of Jesus' parables, we bluntly declare, "We do not want this man to reign over us" (Luke 19:14b). But Christ hasn't changed, and neither has His power to forgive us and save us. Have you given your life to Him?