"Nevertheless do not rejoice in this, that the spirits are subject to you, but rather rejoice because your names are written in heaven."
Churchmen are to rejoice (always), but we need to be a bit careful concerning those things about which we delight. The disciples (above) were thrilled that the devil cowered before them. Christ, on the other hand, would have them direct their excitement to the fact that they were sealed in heaven, by the blood of the Lamb.
The church's conquest of sin, sinners, Satan, and his demons is all a good thing. But we must always keep in mind the fact that God takes pleasure in positive salvation much more than He does the destruction of the wicked--and so should we.
[Puritan quote of the day: "Do you wonder why the grace of God has found such enemies as it always has, especially in religions in which works are mingled with grace?" --Richard Sibbes, in "Glorious Freedom"]