The context of Matthew 10:34 and Luke 12:51 is about how following Jesus can bring division and it isn't an easy choice.
Question: "What did Jesus mean by coming to bring a sword in Matthew 10:34-36?"
Answer: Matthew 10:34–36 describes Jesus telling the disciples that He came not to bring peace to the world, but a sword. Jesus’ sword was never a literal one. In fact, when Peter took up a sword to defend Jesus in the Garden of Gethsemane, Jesus rebuked him and told him to put away his sword, "for all who draw the sword will die by the sword” (
Matthew 26:52). Why then, did Jesus say, “Do not suppose that I have come to bring peace to the earth. I did not come to bring peace, but a sword.” What kind of sword did Jesus come to bring?
Among the names of Jesus Christ is that of
Prince of Peace. Such verses as
Isaiah 9:6,
Luke 2:14, and
John 14:27 make it clear that Jesus came to bring peace, but that peace is between the man and God. Those who reject God and the only way of salvation through Jesus (
John 14:6) will find themselves perpetually at war with God. But those who come to Him in repentance will find themselves at peace with God. Because of Christ’s sacrifice, we are restored to a relationship of peace with God (
Romans 5:1).
Still, it is inevitable that there will be conflict between good and evil, the Christ and the antichrist, the light and the darkness, the children of God (believers) and the children of the devil (those who refuse Christ). Conflict must arise between the two groups, and this can and does happen within a family in which some are believers and others are not. We should seek to be at peace with all men but should never forget that Jesus warned we will be hated for His sake. Because those who reject Him hate Him, they will hate His followers as well (
John 15:18).