False teachers bring false comfort to confused people.  Instinctively they know something is not quite right, but they do not know what.  Persecution also brings confusion to weak believers: should they give up or stay true to Jesus?  Instead, Jude wanted them to be built up in Christ; not abandoned or condemned.  But in the whirlpool of spiritual confusion, churches that have slipped from their spiritual moorings can forget why they exist.  They are to announce eternal life through Jesus Christ, and judgement for those who refuse to believe (John 3:16-18).