At first sight the words used by Jesus in today's Gospel seem strange coming from the mouth of the one who is called the "Prince of Peace". It is necessary then to point out that Jesus is not talking about the Peace that is opposed to War, but to the Peace that is opposed to Division. Division may indeed lead to war but not necessarily so.
Jesus explains that, as a matter of fact, some of the things he says, some of the demands he makes, could lead to serious divisions even within a unit as closely knit as a family. His words may lead, even within a family, to trees flourishing on the bank of a river and chaff blowing on a dry, killing wind as in the Responsorial Psalm. His stance on matters of importance may lead to two slaveries within one family: slavery to sin and a rich, loving, life giving slavery to God.
Jesus is warning his disciples that his teaching may expose fault lines which may exist within any human society, even one as small as family of five.
Would it help, I wonder, if I were to ponder before the Lord the possibility of a serious division between myself and a member of my family whom I admire and respect for his or her genuine goodness and honesty? The split might not be open but might surface if we were confronted with an important moral decision that had to be made. Would I remain a rich flourishing tree by the river and a fruit bearing loving slave of the Lord?
Heavenly Father, make me a loving slave, a flourishing tree within the human family.