I just looked up the context of your quote from Matthew - in Matthew 10, starting in verse 29, Jesus is talking about how very much He loves each of us, even to the numbering of the hairs on our heads, and how much we are worth to Him. Then it is followed by our need to acknowledge Him before others, and being disowned if we don't, followed by the verse you cite.
Jesus is the Prince of Peace, but conflict arises, even within families because of belief in Him.
I don't think it has anything to do with blowing up the entire country of Afghanistan, do you?