Wheter we're ready or not, when Jesus came (when Jesus comes) into the world, it is a time of cataclysmic change for the way we have always done things. Few if any of the people who were alive at the time of Jesus' birth in Bethlehem were aware of the implications of this little-noticed event. Yet the arrival of God's Son into human time and space shook the culture's most basic assumptions to their foundation. When God enters human affairs, our cherished priorities and attitudes are turned upside down so that we have to re-sort our values and remember what is really important.
It may be compared to what happens when a natural event like a great fire or tornado or hurricane devastates a neighborhood. We may receive advance warning, through news broadcasts or our weather-alert radio, and we generally know what to do in order to prepare for an impending disaster. But since we don't know exactly when or how the event will affect us, we have to be ready. As Jesus says, we have to watch (Mark 13:37 RSV).
We have seen the signs. Just as in the time of Jesus' birth, the world is once again in great turmoil. We don't know how or when God will step in to bring about the spiritual changes that we need, to get the world back on track. But Jesus wants his followers to be ready, and so we keep busy doing our assigned tasks; we stay awake, and we watch!