The background to this issue is the Macchabean Revolt, in which the Jews asserted control over the lands of the Seleucid Empire. There were martyrs as described in 2 and 4 Macchabees.
The Jewish ideal was malkut shomain, the Kingship of God. Israel was a theocracy, God was the leader of the nation. Malkut shomain was variously translated to mean the Kingdom of God.
Jesus was preaching the kingdom of God is within you (Luke 7:21) that gathered a large following away from the Temple authorities, and placed the capacity for having a personal relationship with God into the minds and hearts of the devotees of God. This was a threat to Priestly control of the cult of Yahweh in the temples and in the synagogues.
Roman leaders were threatened when they proclaimed Jesus "King"; this caused confusion, and was the strategy the temple priests used to have Jesus tried before Pilate. When Pilate asked "Are you a king?", Jesus replied, "My kingdom is not of this world", meaning the Kingdom of God is within.