In case you haven't noticed, sometimes Jesus says things that are rather difficult to understand, or that turn our ways of thinking upside down. Here's one of them: "Do not think that I have come to bring peace on earth; I have not come to bring peace, but a sword" (Matthew 10:34).
Jesus is not some great political (or even religious) figure who came to unite all peoples, end all wars, and provide for social and economic equality for all. What I've just described is actually how the antichrist is expected to dominate the world order. Rather, Jesus came to reveal his Father and to save our souls, and "keeping the peace" is inadequate to his task.
What is the sword of which Jesus speaks, the one that is more central to his mission than bringing peace? It is certainly not the sword of malicious aggression, of violent crime, or of anything that proceeds from hatred. There are actually several edges to this sword, and the one referred to in the context of the passage quoted above has to do with the division that always results when divine truth is proclaimed. Jesus said that our enemies will be within our own house, that is, people will be set against one another, even against their closest relatives, because some will believe in Him and some won't. It's not that Jesus desires this division, but that his coming will inevitably produce it. Some will stand for the truth and some will stand against it. St Simeon prophesied this when Jesus was but an infant: "this child is set for the fall and rising of many in Israel, and for a sign that is contradicted..." (Luke 2:34). Trying to make a superficial "peace" by ignoring the sword of division between those who accept Christ and those who don't (relativism is a handy tool here), is not doing the will of Christ. "Do not think that is why I have come," says the Lord. Jesus' answer to the division is not relativism but evangelization, not tolerance but an invitation to repentance and conversion.
There is also the sword of spiritual warfare. There can be no peace, no truce, between the followers of Jesus and "the spiritual hosts of wickedness." We have to stand against evil without compromise, wherever we find it--starting first with ourselves. "The sword of the Spirit, which is the word of God" (Ephesians 6:17) is like the Surgeon's scalpel that must be applied to our sinful habits or inclinations, so that we can fight the good fight with a pure heart. If we are to wield the sword against the evil one, we have first to cut out the evil in ourselves. "For the word of God is...sharper than any two-edged sword, piercing to the division of soul and spirit...discerning the thoughts and intentions of the heart" (Hebrews 4:12).
Peace is certainly desirable, but not at the price of truth, righteousness, and the will of God. To be a disciple of Christ is to be equipped for battle--not to harm or destroy our fellow men, but to wield the sword of the Spirit against all falsehood and evil, all that sets itself against the will of God for our salvation. "For we are not contending against flesh and blood, but against...the world rulers of this present darkness, against the spiritual hosts of wickedness" (Ephesians 6:12). No peace with them, only the sword.