Christianity IS A Mystery Religion

I noticed in passing a Christian author rejecting a cult (I think it was Mormonism) as non-Christian because it had a goddess, which indicates oneness. He said that that made it a mystery religion. I agree that mormonism is a cult, perhaps semi-Christian at best, but Christianity nevertheless IS a mystery religion. In Jesus' native language, Aramaic, all reference to the Holy Ghost is feminine gender. THAT was the holy ground Jesus stood on before any of it was translated into Greek.