For a Byzantine angle on Huckabee’s remark about Mormon beliefs (“Don’t Mormons believe that Jesus and the devil are brothers?”), I would note that the belief in the fraternity of Jesus and the devil has some loose similarities with the beliefs ascribed to the Bogomils, who allegedly taught something similar about Satan and Michael.  Aside from these associations, there is a more fundamental problem that this belief contradicts the understanding of Christ as the only-begotten (monogenes) Son, co-unoriginate with the Father.     

Update: In the “Huckabee is not running a sectarian campaign” file, you can add his apology to Romney for these entirely innocent remarks.