Both groups try and remove the hinge point of the bible from the anointing work of Jesus dying on the cross and the New Testament to later texts and works.
Essentially both groups have turned Christianity into Star Wars. Growing up ( depending how old you are ) you basically think there are is only three movies. The death star blows up and it is over.
No, No, No.............the story keeps growing and changing. Too much money to be made.
Also both religions are an exclusive club in which salvation depends on becoming a member. Kind of like shopping at Costco.