“Sanctify yourselves against to morrow: for thus saith the Lord God of Israel, There is an accursed thing in the midst of thee, O Israel: thou canst not stand before thine enemies, until ye take away the accursed thing from among you.” Joshua 7:13

A valuable lesson can be learned from Joshua. First, we are called to sanctify ourselves and second, we cannot fight the battle that God has called us to fight if we have unholy things in our midst.