Can Church A Badmouth Church B?

There are four possible scenarios: 
Church A - The church
badmouthing Church B		   Church B - The church suffering
the verbal attack

Scenario Four:  
Neither Church A nor Church B
are true churches of God
This scenario is rather moot.  Even so, even a false church, with a nominal belief in Christian principles could not find justification for attacking individuals and other churches. 
0002-A
0002-B
0000-C