If history has shown us anything, we Christians are incompetent when it comes to interpreting the signs of the present age.
At Mass today the Gospel passage is taken from St. Luke's account, and it seems like two completely unrelated paragraphs (Lk. 12.49-56). In the first, Jesus talks about His mission, and it's not a pretty picture. In the second he talks about His contemporaries not being able to read the signs all around them (so apparently first century Jews were just as bad at reading signs...must be a family trait).
The fact of the matter is that the one grows out of the other. People read signs poorly, and while some may understand the implications of the events around them, but others, even in the same family household, most definitely will not. And it will not be peaceable.
The thrust of the passage is that Jesus' mission will be divisive. We actually know in hindsight that it was, it is divisive. Everyone around Our Lord were looking at current events and making suppositions, and most of those suppositions were wrong. Those few who were right were drowned out or even snuffed out. Rome was the real enemy. Rome could be defeated. The Messiah would come and lead Israel to drive Rome out of the promised land.
Wrong. Wrong. Wrong.
In only a few short decades Rome would destroy the Holy City as completely as Nebuchadnezzar did centuries before. Less than a century after that Rome completely obliterated any vestige of Judea as a political entity and named the land after Israel's mortal enemies, the Philistines. Rome was an enemy indeed, but there was no Messiah to lead Israel to kick Rome out, no army that could withstand the hammer that Rome levied at the last vestige of the Kingdom of Israel.
Our Lord stated that He had a baptism yet to be completed. That baptism He mentioned was His Passion, Death, and Resurrection. The real enemy He came to combat as Messiah was not Rome, but Death and Sin. Rome was but an annoyance...a painful, disruptive, evil annoyance, but not the root evil. Yet no household within Judea fully agreed or disagree on this point. Jesus' mission indeed set a fire and split households.
Today we see much the same thing. How many of us try to co-opt God, to draft Jesus, into our political agenda? How much do we try to cram God into the presuppositions of our personal to-do lists, our own wishes, our own goals? How many of us look at current events and try to spin them to match our prejudices and our desires? How many of our families are divided and at each others' throats over what each of us perceive to be God's Will or the "true" interpretation of Scripture, Tradition, or Reason?
To be honest, most of us. As Isaiah writes in the Old Testament lesson for Mass (Is. 5.1-7), we have all of us become not the well-cultured vintage that God has intended but instead have become wild grapes, bitter, sour, and totally unsuited for the work of God's Kingdom. We have failed to read the present time.
Our appropriate response should be one of repentance and humility. As the psalm for today writes, our prayer should be, "Turn now, O God of hosts, look down from heaven; behold and tend this vine; / preserve what your right hand has planted," (Ps. 80.14) and then we should really listen to what God calls us to do, to step out of ourselves and our desires and our agenda and focus on Him and those whom He loves, that is, our fellow humans.