LONDON—A British teenager was found guilty on Tuesday of murdering two sisters, as part of a pact he believed he had made with demonic forces to kill at least six women every six months in exchange for a future lottery win. Danyal Hussein, now 19, stabbed to death Bibaa Henry, 46, and Nicole Smallman, 27, in a savage attack in a country park in northwest London in June last year after they had celebrated Henry’s birthday with friends, police said. Hussein had carried out the murders to fulfill his side of a “contract” with the demon “Mighty King Lucifuge Rofocale”, which he signed using his own blood, promising to “perform a minimum of six sacrifices every six months for as long as I am free and physically capable”, police told reporters. Hussein wrote that he hoped his reward would be to “win the Mega Millions Super Jackpot”, and police found …