Many would extend that argument to include Muslims as well since they also "believe" in Christ.
Mormons deny the Deity of Christ and the Trinity in general. In fact, they go so far as to believe that Jesus was a brother of the Devil.
If you want to believe that's Orthodox christianity, that's up to you. But I would bet your Catholic authorities would not agree with your opinion.
I wonder what YHvH thinks about the millions who worship the goddess of heaven.
b'SHEM Yah'shua
Why would you call them my authorities? I have not given jurisdiction over my soul or my mind. One of the chief messages of Christ, and the one he was killed for, was that we each have a personal, direct relationship with God. We do not need priests manning the toll booths on the highway to heaven or manning the Pearly Gates.