Whether they know it or not.

The very first degree of Freemasonry results in the noob Mason getting a Masonic apron made out of lambskin. They use lambskin for their aprons in a blasphemous, futile attempt to cover their nakedness, as if a connection to the Lamb will protect them...somehow, that the Creator may not directly see their nakedness. Of course that's a lie, just like all their other nonsense.