God Reveals Why Israel Was Defeated

Joshua 7:10-12
 
10  And the LORD said unto Joshua, Get thee up; wherefore liest thou thus upon thy face? 
11  Israel hath sinned, and they have also transgressed my covenant which I commanded them: for they have even taken of the accursed thing, and have also stolen, and dissembled also, and they have put it even among their own stuff. 
12  Therefore the children of Israel could not stand before their enemies, but turned their backs before their enemies, because they were accursed: neither will I be with you any more, except ye destroy the accursed from among you.