Among Jesus' teachings, there was mention of a kingdom of God. Once followers of Jesus become part of God's family, they still need to abide by guidelines in the Bible. Metaphorically, God represents the king who takes care of His subjects. As in Medieval times, people residing within the kingdom have to earn their keep. Jesus uses parables to provide parallels of the kingdom of God to what we know of life on Earth. All 4 books of the Gospels make mention of the kingdom of God; but, Luke contains the most extensive coverage on this topic.