Joshua 3:5

And Joshua said to the people, "Sanctify yourselves for tomorrow the Lord will do wonders among you."  Joshua 3:5

The word "sanctify" means to be set apart for a special purpose, to be made holy.  In terms of our walk with the Lord, it refers to the process by which the Holy Spirit conforms us to the image of Christ, and empowers us to overcome the flesh (sin).

For Joshua, the Lord doing "wonders" among the people was directly tied to their sanctification.  The same can be said of churches today.  Often, we say we long for God to do something great in our church.  But for many churches it's been a long time since they've seen God do anything out of the ordinary.  Why is this?

In many (most?) instances, this is because the people of the church are not living sanctified/holy lives.  God will not "do wonders" where unconfessed sin lingers.  When the church is nothing more than a slightly sanitized version of the world, we should not expect to see God move.

If we truly want to see God revive our churches, then we must deal with any/all sin that is in the camp.