SWK speaks about the existence of HM.
Spencer W. Kimball, as quoted in Edward L. Kimball, comp., The Teachings of Spencer W. Kimball (Salt Lake City: Deseret Book, 1982), 52
Now, the sealing for eternity gives to you eternal leadership. The man will have the authority of the priesthood, and if he keeps his life in order he will become a god. Now, that’s hard to understand, isn’t it? But that’s the way it is. You see, we have a Father in Heaven and we have a mother in heaven. And so we have a spiritual father and mother as we have a material father and mother on the earth. The Lord created this earth for us and made it a beautiful place to live. He promised us that if we would live the right way we could come back to him and be like him.