Will you please explain why Jesus sounds harsh in Matthew 10:34-36?
"Behold, I send you out as sheep in the midst of wolves. Therefore be wise as serpents, and harmless as doves. But beware of men: for they will deliver you up to councils, and in their synagogues they will scourge you. Yes, and you will be brought before governors and kings for my sake, for a testimony to them and to the nations. But when they deliver you up, don't be anxious how or what you will say, for it will be given you in that hour what you will say. For it is not you who speak, but the Spirit of your Father who speaks in you. Brother will deliver up brother to death, and the father his child. Children will rise up against parents, and cause them to be put to death. You will be hated by all men for my name's sake, but he who endures to the end will be saved. But when they persecute you in this city, flee into the next, for most certainly I tell you, you will not have gone through the cities of Israel, until the Son of Man has come. A disciple is not above his teacher, nor a servant above his lord. It is enough for the disciple that he be like his teacher, and the servant like his lord. If they have called the master of the house Beelzebul, how much more those of his household! Therefore don't be afraid of them, for there is nothing covered that will not be revealed; and hidden that will not be known. What I tell you in the darkness, speak in the light; and what you hear whispered in the ear, proclaim on the housetops. Don't be afraid of those who kill the body, but are not able to kill the soul. Rather, fear him who is able to destroy both soul and body in Gehenna. Aren't two sparrows sold for an assarion coin? Not one of them falls on the ground apart from your Father's will, but the very hairs of your head are all numbered. Therefore don't be afraid. You are of more value than many sparrows. Everyone therefore who confesses me before men, him I will also confess before my Father who is in heaven. But whoever denies me before men, him I will also deny before my Father who is in heaven. Don't think that I came to send peace on the earth. I didn't come to send peace, but a sword. For I came to set a man at odds against his father, and a daughter against her mother, and a daughter-in-law against her mother-in-law. A man's foes will be those of his own household. He who loves father or mother more than me is not worthy of me; and he who loves son or daughter more than me isn't worthy of me. He who doesn't take his cross and follow after me, isn't worthy of me. He who seeks his life will lose it; and he who loses his life for my sake will find it" (Matthew 10:16-39).
In Matthew 10, Jesus is giving instructions to his disciples prior to sending them out into the region. One topic is the fact that what they will be teaching will not be well-received by all who hear it. They will be facing persecution at the hands of the religious rulers and the secular government. But Jesus warns that even members of their own families may turn against them.
Unlike the popular notion circulated today, Jesus' goal was not to teach peace at any price. Jesus and his followers taught the truth. Those who accept the truth find peace in their lives, but the sad fact is that there are people who are not interested in the truth. They find the truth so discomforting that they will actually fight it. "This is the judgment, that the light has come into the world, and men loved the darkness rather than the light; for their works were evil. For everyone who does evil hates the light, and doesn't come to the light, lest his works would be exposed" (John 3:19-20).
Christianity is not about getting along with people in this world. This world, by its very nature, is caught up in sin. "Don't love the world, neither the things that are in the world. If anyone loves the world, the Father's love isn't in him" (I John 2:15). Christians are commanded to lead people out of sin. But that is going to cause conflict with those who prefer their sins. "If you were of the world, the world would love its own. But because you are not of the world, since I chose you out of the world, therefore the world hates you" (John 15:19).
As a result, we are in a battle, not a secular physical battle, but a battle for the hearts and minds of men. "For though we walk in the flesh, we don't wage war according to the flesh; for the weapons of our warfare are not of the flesh, but mighty before God to the throwing down of strongholds, throwing down imaginations and every high thing that is exalted against the knowledge of God, and bringing every thought into captivity to the obedience of Christ" (II Corinthians 10:3-5).