Why did the KKK "light" aka burn crosses? So, the KKK claimed itself to be a "Christian" organization, originally based on a lot of anti-Catholic and obviously anti-Black sentiment.  Famously, one of their intimidation techniques was to burn a cross, making others aware of their presence.

This surprises me - that any organization that claimed the name of Christ, no matter how bogus the claim - would do what appears to me to be sacrilege to its most potent symbol.  I have heard the claim that the KKK was 'lighting' the cross, not burning it, but that seems a bit of a stretch.

Is there any evidentiary / primary source material that corroborates this explanation, and more importantly, provides some form of theological or biblical justification for the practice?
The Knight's Party website appears to be the official voice for the KKK today. Their FAQ contains the following question and answer:


  Q. Why do you burn the cross?
  
  A. Many have been led to believe the Klan burns the cross as an act of
  desecrating a Christian symbol. Nothing could be further from the
  truth. The lighted cross is an old symbol used on the hillsides of
  Scotland. Many churches today use the lighted cross as a symbol. The
  Methodist church uses the cross with flames at its base sweeping up
  and around the cross. The Lutheran church uses the symbolism. When the
  Klan was founded there was not electricity. They could not light up a
  cross the way we light up a Christmas tree. Fire was used. The fire
  was used to symbolize the fiery light of Christ – a metaphor often
  used in the Bible. The Cross obviously is a symbol of Christianity.
  The Cross lighting ceremony gives honor to Jesus Christ.


and


  It is no more a desecration of the cross than it is for the American Legion to respectfully lay to peace an American flag by setting it on fire – which is the correct procedure.


Other references echo the sentiment that, instead of destroying, they feel that they are honoring the cross. The reasoning appears to be primarily based on tradition rather than a particular scripture passage.