In his letter to the Galatians, one of yesterday's readings (Gal 6:14-18), Paul says, "let no man trouble me; for I bear on my body the marks of Jesus". In yesterday's Gospel (Luke 10:1-12, 17-20), however, we read that "the harvest is plentiful, but the laborers are few" and that Jesus sent His disciples out "as lambs in the midst of wolves".
We are outnumbered by a very real, very powerful enemy. We are among the wolves. And here's the shocker - we can't beat them. We can't win the war for ourselves.
Jesus goes on: "Behold, I have given you authority to tread upon serpents... the power to tread upon serpents... Nevertheless, do not rejoice in this, that the spirits are subject to you; but rejoice that your names are written in heaven."
While God gives us the power to fight, the fight is not the end, only the means. Its our battle to fight but not ours to win. Christ struck the fatal blow to Satan's schemes on the cross, and we wait for Him to return and claim ultimate, everlasting victory in the war. The battles we fight are those of a victorious army leaving the field; the enemy is taking its final, parting shots. Those shots can be just as deadly, though, and we must be careful not to be taken on our way to victory.
We can't lost sight of the point of the battle - not to win the war, which Christ has done because we could not, but to fight and survive, to rejoice in the end because our names remain written in heaven.