Read: Acts 17:1-9
And Paul went in, as was his custom, and on three Sabbath days he reasoned with them from the Scriptures, explaining and proving that it was necessary for the Christ to suffer and to rise from the dead, and saying, “This Jesus, whom I proclaim to you, is the Christ.” (Acts 17:2, 3 ESV)
Jesus died. But he didn't stay dead. He returned to life. He ascended, bodily, into Heaven. He went before us into death, and then into resurrected eternity, to prepare the path that who belong to the kingdom of God will one day travel.
Upon his conversion Saul of Tarsus, an infamous persecutor, became an enthusiastic proclaimer of Jesus. He often went into Jewish Synagogues to teach about Jesus, no doubt hoping to bring the truth to his people. He was articulate, and intelligent, persuading a great many people to open their hearts to Jesus—the Christ and King.
It was Jesus' role as Christ which infuriated the Jews; but it was his role as King which the legality of persecution stemmed from. Salvation can come from no source but Jesus. That hasn't stopped a multitude of people from attempting to save themselves, but it is folly.
Just as errant is the rejection of Jesus Christ as King. People often refuse to acknowledge any authority that is not of their own making. They want the throne of their lives left alone. We like to play King, Jesus is both Christ the Savior and the King of kings.